BR112019019985A2 - communication method, source base station, target base station, main network device, and terminal device - Google Patents

Abstract

embodiments of the present invention disclose a communication method, a source base station, a target base station, a main network device, and a terminal device, wherein the method includes: sending a request via a source base station of automatic switching to a target base station, where the automatic switching request is used to request the automatic switching of a session from a terminal device from the source base station to the target base station, and the automatic switching request includes an identifier of a session requested to be changed automatically and indication information for a network slice corresponding to the session; and receiving, from the source base station, an automatic change response message from the target base station, where the automatic change response message includes rejection indication information, and rejection indication information is used to indicate information of cause corresponding to a session, which is rejected by the target base station due to a network slice, from the session requested to be changed automatically. this request can increase an automatic switching success rate.

Description

“COMMUNICATION METHOD, SOURCE BASE STATION, TARGET BASE STATION, MAIN NETWORK DEVICE, AND TERMINAL DEVICE”

TECHNICAL FIELD [0001] The present invention relates to the field of communication technologies and, in particular, to a communication method, to a source base station, to a target base station, to a main network device and to a terminal device.

FUNDAMENTALS [0002] A concept of a network slice is introduced in 5G. A terminal device currently performs a plurality of sessions and network slices corresponding to the different sessions are required to serve the sessions. In this case, if the terminal device needs to access a network and establish a plurality of sessions, a base station connected to the terminal device will need to support the network slices corresponding to all sessions or some sessions on the terminal device.

[0003] Under the circumstances, it is worth considering how to increase an automatic changeover success rate.

SUMMARY [0004] To solve a technical problem, modalities of the present invention provide a communication method, a source base station, a target base station, a main network device and a terminal device, in order to increase a success rate automatic switching.

[0005] According to a first aspect, an embodiment of the present invention provides a method of communication, including:

send, through a source base station, an automatic change request to a target base station, where the automatic change request is used to request the automatic change of a session from a terminal device from the source base station to the target base station, and the automatic change request includes an identifier of a requested session to be changed automatically and indication information for a network slice corresponding to the session; and receiving, by the source base station, an auto-change reply message from the target base station, where the auto-change reply message includes

Petition 870190095647, of 09/24/2019, p. 82/212

2/94 bounce indication information, and bounce indication information is used to indicate cause information corresponding to a session, which is rejected by the target base station due to a network slice, from the session requested to be automatically changed.

[0006] In the first aspect, the source base station can obtain, using the target base station, the cause information that corresponds to the session, which is rejected by the target base station due to a network slice, to help to provide the information for another session that needs to be requested to be automatically switched to the target base station. When a session corresponding to the same network slice needs to be switched automatically from the source base station, the source base station can directly determine whether the session can be automatically switched to the target base station, thereby increasing a rate automatic change success.

[0007] With reference to the first aspect, in an optional implementation, the source base station sends an automatic change command to the terminal device if the automatic change response message is an automatic change request confirmation message, where the automatic change command includes relay indication information corresponding to the session that is rejected by the target base station, and relay indication information corresponding to the session is used to indicate whether the terminal device is allowed to route to a network slice supported by the target base station, a rejected session data stream. Optionally, the retransmission indication information may not indicate a specific network slice to which the data stream is routed. In this way, the terminal device can obtain which sessions can still be reestablished at the target base station after rejection, thereby improving the flexibility of automatically changing the session.

[0008] With reference to the first aspect, in an optional implementation, the method further includes: sending, by the source base station, an RRC radio resource control connection release message to the terminal device if the response message from automatic shift is an automatic shift failure message. Optionally, the RRC connection release message includes indication information for a slice of

Petition 870190095647, of 09/24/2019, p. 83/212

3/94 network supported by a neighboring cell to a source cell, indication information for a network slice supported by a TA / RA to which the neighboring cell of the source cell belongs, or information about a network slice supported by a base station neighboring the source base station. In this case, the terminal device can release an RRC connection as soon as possible, to avoid a subsequent radio link failure and reduce overhead signaling costs.

[0009] According to a second aspect, an embodiment of the present invention provides a method of communication, including:

receive, by a target base station, an automatic change request from a source base station, where the automatic change request is used to request an automatic change of a session from a terminal device from the source base station to the target base station, and the automatic change request includes an identifier for a requested session to be changed automatically and indication information for a network slice corresponding to the session; and sending, through the target base station, an automatic change response message to the source base station, where the automatic change response message includes rejection indication information, and rejection indication information is used to indicate information of cause corresponding to a session, which is rejected by the target base station due to a network slice, from the session requested to be changed automatically.

[0010] In the second aspect, the target base station can notify the source base station of the cause information that corresponds to the session, which is rejected due to a network slice of the target base station, to help provide information to another session that is at the source base station and needs to be requested to be automatically switched to the target base station. When a session corresponding to the same network slice needs to be switched automatically from the source base station, the source base station can directly determine whether the session can be automatically switched to the target base station, thereby increasing a rate automatic change success.

[0011] With reference to the second aspect, in an implementation

Petition 870190095647, of 09/24/2019, p. 84/212

4/94 optional, the target base station receives an automatic change confirmation message from the terminal device, and the target base station sends a path switching request to a main network device, where the switching request from trajectory includes a session identifier that is accepted by the target base station and a session identifier that is rejected by the target base station; and the target base station receives a path switch request response message from the primary network device, where the path switch request response message includes an identifier of a session for which the path switch was performed. completed successfully. In this case, the main network device performs the path switch in the accepted session.

[0012] According to a third aspect, an embodiment of the present invention provides a method of communication, including:

receive, by a main network device, a trajectory switch request from a target base station, where the trajectory switch request includes a session identifier that is accepted by the target base station and an identifier from a session that is rejected by the target base station; perform, by the main network device, the trajectory switching in the accepted session, and perform deactivating or releasing the rejected session; and sending, via the main network device, a path switching request response message to the target base station, where the path switching request response message includes an identifier of a session for which the path switching has been successfully completed.

[0013] In the third aspect, the accepted session identifier and the rejected session identifier are carried in the trajectory switching request, so that the main network device can determine a disabled session from all stored sessions of the terminal device . In this way, the primary network device does not need to handle such sessions, and only needs to handle the accepted session and the rejected session, thereby improving processing efficiency.

[0014] With reference to the first aspect or the second aspect, in a possible implementation, the session requested to be changed automatically includes a first session, and a network slice

Petition 870190095647, of 09/24/2019, p. 85/212

5/94 corresponding to the first session is supported by the target base station. In this case, the target base station does not need to perform admission control in a second session, thereby saving processing time to perform admission control in the second session. Alternatively, the session requested to be switched automatically includes a first session and a second session, a network slice corresponding to the first session is supported by the target base station, and a network slice corresponding to the second session is not supported by the base station. target. Therefore, the target base station can directly determine a session that is not supported by the target base station, thereby improving the effectiveness of determining an automatic change response message. Certainly, special classification processing may not be performed for all sessions that need to be changed automatically.

[0015] With reference to the first aspect, the second aspect or the third aspect, in a possible implementation, the cause information is: the target base station does not support a network slice corresponding to the rejected session, or a resource is not available for a network slice being supported by the target base station and corresponding to the rejected session.

[0016] With reference to the first aspect or the second aspect, in a possible implementation, if the automatic change response message is an automatic change request confirmation message, the automatic change response message additionally includes indication information retransmission corresponding to the session that is rejected by the target base station, and the retransmission indication information corresponding to the session is used to indicate whether the terminal device is allowed to route, to a network slice supported by the target base station, a stream data from the rejected session. In this way, the terminal device can obtain which sessions can still be reestablished at the target base station after rejection, thereby improving the flexibility of automatic session switching.

[0017] With reference to the first aspect or the second aspect, in an optional implementation, if the automatic change response message is an automatic change request confirmation message, the automatic change request confirmation message

Petition 870190095647, of 09/24/2019, p. 86/212

6/94 further includes an identifier of a rejected carrier or an identifier of a rejected data stream of the requested session to be changed automatically, so that the source base station can recognize the rejected carrier or the rejected data stream.

[0018] With reference to the first aspect or the second aspect, in an optional implementation, an automatic change request response message additionally includes information about the supported network slice of the target base station. This helps the target base station notify the source base station of information about a network slice currently supported by the target base station, thereby reducing the interaction between the source base station and the target base station.

[0019] With reference to the second aspect or the third aspect, in an optional implementation, the request for switching the trajectory additionally includes information for indicating the network slice corresponding to the session that is rejected by the target base station. In this case, the main network device can compare the network slice corresponding to the rejected session with a network slice that is supported by a target base station and which is stored on the main network device, to obtain whether the session is rejected because the target base station does not support the network slice. If so, the primary network device subsequently triggers a session removal (remove) process to reduce the storage space occupied by such sessions on the primary network device. If not, the primary network device can subsequently trigger a session deactivation (deactivate) process, so that the primary network device can quickly resume the session when the session needs to be activated.

[0020] With reference to the second aspect or the third aspect, in an optional implementation, the request for switching the trajectory additionally includes the cause information corresponding to the session that is rejected by the target base station. Cause information is carried over, so that the main network device can perform different processing in sessions that are rejected for different causes.

[0021] According to a fourth aspect, an embodiment of the present invention provides a method of communication, including:

receive, by a terminal device, a

Petition 870190095647, of 09/24/2019, p. 87/212

7/94 RRC radio resource control connection from a source base station; and releasing an RRC connection, where the RRC connection release message includes indication information of a supported network slice from a neighboring cell of a source cell, indication information of a supported network slice from a TA / RA which the neighbor cell of the source cell belongs to or information about a supported network slice of a base station neighboring the source base station.

[0022] In the fourth aspect, the terminal device can release the RRC connection as soon as possible, to avoid a failure in the subsequent radio link and to reduce the overhead costs of signaling.

[0023] According to a fifth aspect, an embodiment of the present invention provides a method of communication, including:

send, through a source base station, a first automatic change request to a primary network device, where the first automatic change request is used to request the automatic change of a session from a terminal device from the source base station for a target base station, and the first automatic change request includes information about the target base station and an identifier for a session requested to be changed automatically; and receiving, by the source base station, a first automatic change response message from the main network device, where the first automatic change response message includes rejection indication information, and rejection indication information is used to indicate cause information corresponding to a session, which is rejected by the target base station due to a network slice, from the session requested to be changed automatically.

[0024] In the fifth aspect, the source base station can obtain, using the main network device, the cause information that corresponds to the session, which is rejected by the target base station, due to a network slice, for help provide information for another session that needs to be requested to be automatically switched to the target base station. When a session corresponding to the same network slice needs to be changed automatically from the source base station, the source base station can directly determine whether the session can be

Petition 870190095647, of 09/24/2019, p. 88/212

8/94 automatically switched to the target base station, thereby increasing an automatic switching success rate.

[0025] With reference to the fifth aspect, in a possible implementation, the method additionally includes: sending, through the source base station, an automatic change command to the terminal device if the first automatic change response message is a first automatic change request confirmation, where the automatic change command includes retransmission indication information corresponding to the session that is rejected by the target base station, and the relay indication information corresponding to the session is used to indicate whether the terminal device has permission to route, to a supported network slice from the target base station, a rejected session data stream. Optionally, the retransmission indication information may not indicate a specific network slice to which the data stream is routed. In this way, the terminal device can obtain which sessions can still be reestablished at the target base station after rejection, thereby improving the flexibility of automatic session switching.

[0026] With reference to the fifth aspect, in a possible implementation, the method additionally includes: sending, by the source base station, an RRC connection release message to the terminal device if the first automatic change response message is a first automatic change failure message. Optionally, the RRC connection release message includes indication information of a supported network slice from a cell neighboring the source base station, indication information of a supported network slice from a TA / RA which the cell neighboring the station source base belongs, or information about a supported network slice from a neighboring base station to the source base station. In this case, the terminal device can release an RRC connection as quickly as possible, to avoid subsequent radio link failure and reduce signaling overhead.

[0027] According to a sixth aspect, an embodiment of the present invention provides a method of communication, including:

receive, by a main network device, a first automatic change request from a source base station, where the first

Petition 870190095647, of 09/24/2019, p. 89/212

9/94 automatic change request is used to request automatic change of a session from a terminal device from the source base station to a target base station, and the first automatic change request includes information about the target base station and an identifier of a session requested to be changed automatically; and sending, through the main network device, a first automatic change response message to the source base station, where the first automatic change response message includes rejection indication information, and rejection indication information is used to indicate cause information corresponding to a session, which is rejected by the target base station due to a network slice, from the session requested to be changed automatically.

[0028] In the sixth aspect, the main network device can notify the source base station of the cause information that corresponds to the session, which is rejected by the target base station, due to a network slice, to help provide information to another session that is at the source base station and needs to be requested to be automatically switched to the target base station. When a session corresponding to the same network slice needs to be switched automatically from the source base station, the source base station can directly determine whether the session can be automatically switched to the target base station, thereby increasing a rate automatic change success.

[0029] With reference to the sixth aspect, in a possible implementation, before the sending, by the main network device, of a first automatic change response message to the source base station, the method additionally includes: sending, by the main network, a second automatic change request to the target base station, where the second automatic change request includes a session identifier and indication information for a network slice corresponding to the session; and receiving, by the main network device, a second automatic change response message from the target base station, where the second automatic change response message includes the rejection indication information. In this way, the main network device notifies the source base station of the rejection indication information.

Petition 870190095647, of 09/24/2019, p. 90/212

10/94 [0030] According to a seventh aspect, an embodiment of the present invention provides a method of communication, including:

receiving, by a target base station, a second automatic change request from a main network device, where the second automatic change request includes a session identifier and indication information for a network slice corresponding to the session; and sending, through the target base station, a second automatic change response message to a source base station, where the second automatic change response message includes rejection indication information, and rejection indication information is used to indicate cause information corresponding to a session, which is rejected by the target base station due to a network slice, from the session requested to be changed automatically.

[0031] In the seventh aspect, the target base station can notify the main network device of the cause information that corresponds to the session, which is rejected by the target base station, due to a network slice, so that the device Main network operator notifies the base station source of the information. This helps to provide information for another session that is at the source base station and that needs to be requested to be automatically switched to the target base station. When a session corresponding to the same network slice needs to be switched automatically from the source base station, the source base station can directly determine whether the session can be automatically switched to the target base station, thereby increasing a rate automatic change success.

[0032] With reference to the fifth aspect, the sixth aspect or the seventh aspect, in a possible implementation, the cause information is: the target base station does not support a network slice corresponding to the rejected session, or a resource that does not is available for a network slice supported by the target base station and corresponding to the rejected session.

[0033] With reference to the fifth aspect or the sixth aspect, in a possible implementation, the first automatic change request additionally includes the first indication information, and the indication information indicates that the source base station does not determine or recognize a supported network slice of the target base station, so that

Petition 870190095647, of 09/24/2019, p. 91/212

11/94 the primary network device obtains that the source base station does not recognize information about the supported network slice of the target base station. Therefore, information about the supported network slice of the target base station can be added to the first auto-change reply message. This reduces the interaction between the source base station and the target base station, and improves the effectiveness of obtaining information about the network slice.

[0034] With reference to the fifth aspect or the sixth aspect, in a possible implementation, the target base station can be a base station that has a communication interface with the source base station, or it can be a base station that has no communication interface with the source base station. Optionally, the first automatic change request may include second indication information indicating that there is no communication interface between the source base station and the target base station. This helps the primary network device to provide information about the supported network slice of the target base station.

[0035] With reference to the fifth aspect or the sixth aspect, in a possible implementation, if the first automatic change response message is a first automatic change request confirmation message, the first automatic change response message additionally includes information retransmission indication values corresponding to the session that is rejected by the target base station, and the relay indication information corresponding to the session is used to indicate whether the terminal device is allowed to route, to a supported network slice of the target base station , a stream of data from the rejected session. In this way, the terminal device can obtain which sessions can still be reestablished at the target base station after rejection, thereby improving the flexibility of automatic session switching.

[0036] With reference to the fifth aspect or the sixth aspect, in a possible implementation, if the first automatic change response message is a first automatic change request confirmation message, the first automatic change request confirmation message includes additionally an identifier of a rejected carrier or an identifier of a rejected data stream of the requested session

Petition 870190095647, of 09/24/2019, p. 92/212

12/94 to be changed automatically, so that the source base station can recognize the rejected carrier or the rejected data stream.

[0037] With reference to the fifth or sixth aspect, in a possible implementation, if the first automatic change response message is a first automatic change request confirmation message, the first automatic change request confirmation message includes additionally information about the supported network slice of the target base station. For example, if the first automatic change request includes the first indication information indicating that the source base station does not determine the supported network slice of the target base station, or the primary network device determines, based on the second indication that they are carried on the first automatic change request and that indicate that there is no communication interface between the source base station and the target base station, that the source base station does not recognize the supported network slice of the target base station , information about the supported network slice of the target base station can be carried. This reduces the interaction between the source base station and the target base station and improves the effectiveness of obtaining information about the network slice.

[0038] With reference to the fifth aspect or the sixth aspect, in a possible implementation, the first automatic change request additionally includes indication information of a network slice corresponding to the requested session to be changed automatically, so that the network device principal can directly determine the indication information of the network slice corresponding to the requested session to be changed automatically. It can be understood that, the first automatic change request may not include the network slice indication information corresponding to the requested session to be changed automatically. This is not limited in this embodiment of the present invention.

[0039] With reference to the fifth aspect or the sixth aspect, in a possible implementation, the first automatic change request additionally includes an identifier of a session data stream that is requested to be changed automatically and that needs to be established and information of QoS corresponding to the data flow. This can save

Petition 870190095647, of 09/24/2019, p. 93/212

13/94 research time, reduce a delay in automatic change and improve the effectiveness of automatic change.

[0040] With reference to the fifth aspect or the sixth aspect, in a possible implementation, the first automatic change request additionally includes AMBR information of aggregated maximum bit rate corresponding to the session. The information is included in the first automatic change request, so that search time is saved, a delay in automatic change is reduced and the effectiveness of automatic change is improved.

[0041] With reference to the sixth aspect or the seventh aspect, in a possible implementation, the session included in the second automatic change request is a first session, and a network slice corresponding to the first session is supported by the target base station. In this case, the target base station does not need to perform admission control in a second session, thereby saving processing time to perform admission control in the second session. Alternatively, the session included in the second automatic change request is the first session and a second session, a network slice corresponding to the first session is supported by the target base station, and a network slice corresponding to the second session is not supported by the station. target base. Therefore, the target base station can directly determine a session that is not supported by the target base station, thereby improving the effectiveness of determining an automatic change response message. Certainly, special classification processing may not be performed for all sessions that need to be changed automatically.

[0042] With reference to the sixth aspect or the seventh aspect, in a possible implementation, if the second automatic change response message is a second automatic change request confirmation message, the second automatic change response message additionally includes information relay indication corresponding to the session which is rejected by the target base station, and the relay indication information corresponding to the session is used to indicate whether the terminal device is allowed to route to a supported network slice of the base station target, a data stream from the

Petition 870190095647, of 09/24/2019, p. 94/212

14/94 session rejected. In this way, by using the source base station, the main network device can obtain which sessions can still be reestablished at the target base station after rejection, thereby improving the flexibility of automatic session switching.

[0043] With reference to the sixth aspect or the seventh aspect, in a possible implementation, if the second automatic change response message is a second automatic change request confirmation message, the second automatic change request confirmation message includes additionally an identifier of a rejected carrier or an identifier of a rejected data stream of the session included in the second automatic change request, so that the source base station can recognize the rejected carrier or the rejected data stream.

[0044] In accordance with an eighth aspect, an embodiment of the present invention provides a method of communication, including: sending, through a first base station, a first message to a main network device, where the first message is used to obtain information about a supported network slice for a PLMN from the primary network device; and receiving, by the first base station, a second message from the main network device, where the second message includes information about a supported network slice for a PLMN served by the main network device.

[0045] In the eighth aspect, the first base station can obtain, through the use of the main network device, information of indication of the supported network slice for the PLMN of the main network device, and return, in a PLMN granularity, the supported network slice of the primary network device. This can improve the accuracy of the selection, by the first base station, of a main network device for a session of a terminal device.

[0046] According to a ninth aspect, an embodiment of the present invention provides a method of communication, including: receiving, by a main network device, a first message from a first base station, where the first message is used to obtain information about a supported network slice from the primary network device to a PLMN; and send, via the main network device, a second message to

Petition 870190095647, of 09/24/2019, p. 95/212

15/94 the first base station, where the second message includes information about a supported network slice for a PLMN served by the main network device.

[0047] In the ninth aspect, the main network device can send, to the first base station, information indicating the supported network slice to the PLMN served by the main network device, and return the supported network slice of the device main network (in a PLMN granularity). This can improve the accuracy of the selection, by the first base station, of a main network device for a session of a terminal device.

[0048] According to a tenth aspect, one embodiment of the present invention provides a base station, the base station is a source base station, and the source base station includes: a transmission unit, configured to send a automatic change request to a target base station, where the automatic change request is used to request the automatic change of a session from a terminal device from the source base station to the target base station, and the change request automatic includes an identifier of a session requested to be changed automatically and information indicating a network slice corresponding to the session; and a receiving unit, configured to receive an automatic change response message from the target base station, where the automatic change response message includes rejection indication information, and rejection indication information is used to indicate cause information corresponding to a session, which is rejected by the target base station due to a network slice, from the requested session to be changed automatically.

[0049] Optionally, the source base station can still implement some or all of the optional implementations of the first aspect.

[0050] According to an eleventh aspect, an embodiment of the present invention provides a base station, the base station is a target base station, and the target base station includes: a receiving unit, configured to receive a automatic change request

Petition 870190095647, of 09/24/2019, p. 96/212

16/94 from a source base station, where the automatic change request is used to request the automatic change of a session from a terminal device from the source base station to the target base station, and the request to automatic change includes an identifier of a requested session to be changed automatically and indication information of a network slice corresponding to the session; and a transmitting unit, configured to send an automatic change response message to the source base station, where the automatic change response message includes rejection indication information, and rejection indication information is used to indicate information of cause corresponding to a session, which is rejected by the target base station due to a network slice, from the session requested to be changed automatically.

[0051] Optionally, the source base station can still implement some or all of the optional implementations of the second aspect.

[0052] According to a twelfth aspect, an embodiment of the present invention provides a main network device, and the main network device includes: a receiving unit 1001, configured to receive a path switch request from a target base station, where the path switch request includes a session identifier that is accepted by the target base station and a session identifier that is rejected by the target base station; a processing unit 1002, configured to switch the trajectory in the accepted session, and to deactivate or release the rejected session; and a transmission unit 1003, configured to send a path switch request response message to the target base station, where the path switch request response message includes an identifier of a session for which switching the path. trajectory was successfully completed.

[0053] Optionally, the source base station can still implement some or all of the optional implementations of the third aspect.

[0054] According to a thirteenth aspect, a modality

Petition 870190095647, of 09/24/2019, p. 97/212

17/94 of the present invention provides a terminal device, and the terminal device includes: a receiving unit, configured to receive an RRC radio resource control connection release message from a source base station; and a processing unit, configured to release an RRC connection, where the RRC connection release message includes indication information of a supported network slice from a neighboring cell of a source cell, indication information of a supported network slice from a TA / RA to which the neighbor cell of the source cell belongs, or information about a supported network slice from a base station neighboring the source base station.

[0055] Optionally, the terminal device can also implement the communication method in the fourth aspect.

[0056] According to a fourteenth aspect, an embodiment of the present invention provides a base station, the base station is a source base station, and the source base station includes: a transmission unit, configured to send a first automatic change request for a primary network device, where the first automatic change request is used to request the automatic change of a session from a terminal device from the source base station to a target base station, and the first automatic change request includes information about the target base station and an identifier of a session requested to be changed automatically; and a receiving unit, configured to receive a first automatic change response message from the primary network device, where the first automatic change response message includes rejection indication information, and rejection indication information is used to indicate cause information corresponding to a session, which is rejected by the target base station due to a network slice, from the session requested to be changed automatically.

[0057] Optionally, the source base station can still implement some or all of the optional implementations of the fifth aspect.

[0058] According to a fifteenth aspect, one embodiment of the present invention provides a main network device, and the main network device includes: a receiving unit, configured to receive a

Petition 870190095647, of 09/24/2019, p. 98/212

18/94 first automatic change request from a source base station, where the first automatic change request is used to request the automatic change of a session from a terminal device from the source base station to a base station target, and the first automatic change request includes information about the target base station and an identifier of a session requested to be changed automatically; and a transmitting unit, configured to send a first automatic change response message to the source base station, where the first automatic change response message includes rejection indication information, and rejection indication information is used to indicate cause information corresponding to a session, which is rejected by the target base station due to a network slice, from the session requested to be changed automatically.

[0059] Optionally, the main network device can still implement some or all of the optional implementations of the sixth aspect.

[0060] According to a sixteenth aspect, one embodiment of the present invention provides a base station, the base station is a target base station, and the target base station includes: a receiving unit, configured to receive a second automatic change request from a primary network device, where the second automatic change request includes a session identifier and indication information for a network slice corresponding to the session; and a transmitting unit, configured to send an automatic change response message to the source base station, where the automatic change response message includes rejection indication information, and rejection indication information is used to indicate information of cause corresponding to a session, which is rejected by the target base station due to a network slice, from the session requested to be changed automatically.

[0061] Optionally, the target base station can still implement some or all of the optional implementations of the seventh aspect.

[0062] According to a seventeenth aspect, one embodiment of the present invention provides a base station, and the base station is a first base station, including: a 1101 transmission unit,

Petition 870190095647, of 09/24/2019, p. 99/212

19/94 configured to send a first message to a primary network device, where the first message is used to obtain information about a supported network slice from the primary network device to a PLMN; and a receiving unit 1102, configured to receive a second message from the main network device, where the second message includes information about a supported network slice for a PLMN served by the main network device.

[0063] Optionally, the source base station can still implement some or all of the optional implementations of the seventh aspect.

[0064] According to an eighteenth aspect, an embodiment of the present invention provides a main network device, and the main network device includes: a receiving unit, configured to receive a first message from a first base station , where the first message is used to obtain information about a supported network slice from the main network device to a PLMN; and a transmission unit, configured to send a second message to the first base station, where the second message includes information about a supported network slice for a PLMN served by the main network device.

[0065] Optionally, the source base station can still implement some or all of the optional implementations of the ninth aspect.

[0066] According to a nineteenth aspect, a communications device is provided. The communications device may be the base station in the design of the previous method, or it may be a chip arranged in the base station. The communications device includes a memory, a transceiver and a processor. The memory is configured to store the computer's executable program code and the processor is connected to the memory and transceiver. The program code stored in memory includes an instruction and, when the processor executes the instruction, the communications device is enabled to execute the method performed by the terminal device in any possible design of the first aspect, the second aspect, the fifth aspect, the seventh aspect or the eighth aspect.

[0067] According to a twentieth aspect, a communications device is provided. The communications device can be the main network device in the design of the previous method, or it can be a chip arranged in the

Petition 870190095647, of 09/24/2019, p. 100/212

20/94 main network device. The communications device includes a memory, a transceiver and a processor. The memory is configured to store the computer's executable program code, and the processor is connected to the memory and transceiver. The program code stored in memory includes an instruction and, when the processor executes the instruction, the communications device is enabled to execute the method performed by the network device in any possible design of the third aspect, the sixth aspect or the ninth aspect.

[0068] According to a twenty-first aspect, a communications device is provided. The communications device may be the terminal device in the design of the previous method, or it may be a chip disposed in the terminal device. The communications device includes a memory, a transceiver and a processor. The memory is configured to store the computer's executable program code, and the processor is connected to the memory and transceiver. The program code stored in memory includes an instruction and, when the processor executes the instruction, the communications device is enabled to execute the method performed by the terminal device in any possible design of the fourth aspect.

[0069] According to a twenty-second aspect, a computer program product is provided, and the computer program product includes computer program code. When the computer program code is executed on a computer, the computer is enabled to perform the method in any of the first aspects to the ninth aspect and in the possible implementations of the first aspect to the ninth aspect.

[0070] According to a twenty-third aspect, a computer-readable media is provided, and the computer-readable media stores the program code. When the computer program code is executed on a computer, the computer is enabled to carry out the method in any of the first aspects to the ninth aspect and the possible implementations of the first aspect to the ninth aspect.

[0071] According to a twenty-fourth aspect, a chip is provided, including a processor and a memory. The memory is configured to store a computer program, and the processor is configured to call the computer program from memory and conducted to the

Petition 870190095647, of 09/24/2019, p. 101/212

21/94 computer program. The computer program is used to implement the method in any of the first aspects to the ninth aspect and the possible implementations of the first aspect to the ninth aspect.

BRIEF DESCRIPTION OF THE DRAWINGS [0072] In order to describe the technical solutions in the modalities of the present invention or in the fundamentals more clearly, in the following, the attached drawings necessary to describe the modalities of the present invention or the fundamentals have been briefly described.

[0073] FIGURE 1 is a possible schematic diagram of a communications system architecture according to an embodiment of the present invention;

[0074] FIGURE 2 is a possible schematic diagram of a main network device according to an embodiment of the present invention;

[0075] FIGURE 3 is a schematic flowchart of a communication method according to an embodiment of the present invention;

[0076] FIGURE 4 is a schematic flowchart of another method of communication according to an embodiment of the present invention;

[0077] FIGURE 5 is a schematic flowchart of another method of communication according to an embodiment of the present invention;

[0078] FIGURE 6 is a schematic flowchart of another method of communication according to an embodiment of the present invention;

[0079] FIGURE 7 is a schematic flow chart of another method of communication according to an embodiment of the present invention;

[0080] FIGURE 8 is a schematic structural diagram of a base station according to an embodiment of the present invention;

[0081] FIGURE 9 is a schematic structural diagram of a base station according to an embodiment of the present invention;

[0082] FIGURE 10 is a schematic structural diagram of a main network device according to an embodiment of the present invention;

[0083] FIGURE 11 is a schematic structural diagram of another base station according to an embodiment of the present invention;

[0084] FIGURE 12 is a schematic structural diagram of another

Petition 870190095647, of 09/24/2019, p. 102/212

Main network device according to an embodiment of the present invention;

[0085] FIGURE 13 is a schematic structural diagram of another base station according to an embodiment of the present invention;

[0086] FIGURE 14 is a schematic structural diagram of another base station according to an embodiment of the present invention;

[0087] FIGURE 15 is a schematic structural diagram of another main network device according to an embodiment of the present invention;

[0088] FIGURE 16 is a schematic structural diagram of a terminal device according to an embodiment of the present invention;

[0089] FIGURE 17 is a schematic structural diagram of another base station according to an embodiment of the present invention;

[0090] FIGURE 18 is a schematic structural diagram of another main network device according to an embodiment of the present invention; and [0091] FIGURE 19 is a schematic structural diagram of another terminal device according to an embodiment of the present invention.

DESCRIPTION OF MODALITIES [0092] In the following, the modalities of the present invention are described with reference to the accompanying drawings in the modalities of the present invention.

[0093] The network elements in the embodiments of the present invention are described as follows:

[0094] A terminal device can be a user equipment (UE), and the UE implements one side of the access network by using an access network device. For example, the terminal device can be a portable terminal device, a notebook computer, a subscriber unit, a cell phone (cellular phone), a smartphone (smart phone), a wireless data card, a computer personal digital assistant (PDA), a tablet computer, a wireless modem (modem), a portable device (handheld), a laptop computer (laptop computer), a cordless phone (cordless phone) or a station wireless local loop (WLL), a machine type communication terminal (MTC), or other device that can

Petition 870190095647, of 09/24/2019, p. 103/212

23/94 access a network. The terminal device and the access network device communicate with each other using air interface technology.

[0095] A radio access network (RAN) device is primarily responsible for radio resource management, quality of service (QoS) management, data compression and encryption, and other functions in one side of the air interface. The access network device can include various forms of base stations, for example, a macro base station, a micro base station (also referred to as a small cell), a relay node and an access point. In systems where different radio access technologies are used, a device with a base station function can have different names. For example, the device is referred to as a gNB in a 5- generation system (5th generation, 5G), is referred to an evolved Node B (evolved nodeB, eNB or eNodeB) in an LTE system, or is referred to as a Node B (node B) in a third generation system (3rd generation, 3G).

[0096] A main network device is configured to provide a user connection and perform user management and transport service. For example, establishing a user connection includes functions such as mobility management (mobile management, MM) and paging (paging). User management includes user description, QoS, and security (the corresponding security measures provided by an authentication center include security management of a mobile service and security processing when accessing the external network). A bearer connection includes an external public switched telephone network (PSTN), an external circuit data network, a packet data network, the Internet (Internet) and the like.

[0097] For example, the main network device may include an access and mobility management function (AMF) network element, and is primarily responsible for signaling processing, that is, plan functions control including access control, mobility management, connection and disconnection, and other functions.

[0098] Optionally, the main network device can additionally include a network element of the session management function

Petition 870190095647, of 09/24/2019, p. 104/212

24/94 (session management function, SMF), and is responsible for session management functions, such as session definition, session modification and session release.

[0099] Optionally, the main network device can additionally include a network element of the user plane function (UPF), and is responsible for forwarding and receiving user data on the terminal device. The UPF network element can receive user data from a data network and transmit the user data to the terminal device using the access network device. The UPF network element can also receive user data from the terminal device using the access network device, and forward the user data to the data network. A resource transmission and scheduling function to serve the terminal device on the UPF network element is managed and controlled by the SMF network element. The main network device in the embodiments of the present invention is not limited to the AMF network element, the SMF network element and the UPF network element.

[0100] With reference to FIGURE 1, FIGURE 1 is a possible schematic diagram of a communications system architecture used in an embodiment of the present invention. As shown in FIGURE 1, it can be seen that an access network device can be connected to at least one terminal device. For example, an access network device 101 is connected to both a terminal device 104 and to an end device 105, and an access network device 102 is connected to both an end device 106 and an end device 106. The access network device can be connected to at least one main network device 103. For example, both the access network device 101 and the access network device 102 are connected to the main network device 103.

[0101] There is a control plane interface between the main network device and the access network device. For example, there is an interface between the main network device and the access network, and is referred to as an N2 interface or an NG interface in this application.

[0102] For example, if a communications interface such as an Xn interface exists between the access network device 101 and the device

Petition 870190095647, of 09/24/2019, p. 105/212

25/94 access network 102 in FIGURE 1, the access network device 101 and the access network device 102 can communicate with each other; if no communications interface exists between the access network device 101 and the access network device 102 in FIGURE 1, the access network device 101 and the access network device 102 cannot communicate with each other. Therefore, the access network device 101 and the access network device 102 can respectively transmit, only when there is a communications interface, the information about network slices supported by the access network device 101 and the network device access 102. If there is no communications interface, the access network device 101 and the access network device 102 cannot communicate with each other, and still cannot, respectively, send information about the data slices. supported by the access network device 101 and the access network device 102.

[0103] The main network device 103 can include at least one AMF network element, and optionally can additionally include an SMF network element and an UPF network element. Access network device 102 can be connected to one or more AMF network elements. An AMF network element can support one or more network slices of different types, and the types of network slices supported by different AMF network elements can be different. Each SMF can support one or more network slices of different types, and the types of network slices supported by different SMF network elements can be different. An AMF network element can establish a communication connection with a plurality of SMF network elements. Optionally, an SMF network element can be connected to a plurality of AMF network elements. In addition, an SMF network element can be connected to a plurality of UPF network elements, and an UPF network element can be connected to an SMF network element. In this case, an SMF network element can manage and control a plurality of UPF network elements, and an UPF network element is managed and controlled by an SMF. The UPF network element can establish a connection with the access network device, to implement data transmission from the terminal device.

[0104] For example, with reference to FIGURE 2, FIGURE 2 is a

Petition 870190095647, of 09/24/2019, p. 106/212

26/94 possible schematic diagram of a main network device according to an embodiment of the present invention. An AMF 201 network element establishes a connection with two SMF network elements: an SMF network element 202 and an SMF network element 203. The types of network slice supported by the AMF 201 network element include a type of network slice 1 and a network slice type 2. Network slice type 1 is a network slice type 1, and network slice type 2 is a network slice type 2. The SMF 202 network element is an SMF network element corresponding to network slice 1, and SMF network element 203 is an SMF network element corresponding to network slice 2. An SMF network element can manage and control a plurality of UPF network elements. For example, the SMF 202 network element manages an UPF 204 network element, an UPF 205 network element and an UPF 206 network element, and the SMF 203 network element manages an UPF 204 network element and a network element UPF 208.

[0105] As there is a plurality of types of services in a terminal device, such as enhanced mobile broadband service (enhanced mobile broadband, eMBB), ultra reliable low latency communications (URLLC) , and massive machine type communication, mMTC, the network slices corresponding to different types of service sessions may be different. Due to the different providers provided or services provided, the same type of service can correspond to different network slices. Different access network devices can support different network slices. In this case, if the terminal device needs to access a network and establish a plurality of sessions, an access network device connected to the terminal device will need to support network slices corresponding to all sessions or some sessions on the terminal device.

[0106] Automatic switching to an access network device needs to be performed for the terminal device due to the movement of a terminal device location, load balancing or the like. For example, with reference to FIGURE 1, a session from a terminal device 104 needs to be switched automatically from an access network device 101 to another access network device 102. However, if the automatic change is successful it is closely related to the fact that

Petition 870190095647, of 09/24/2019, p. 107/212

27/94 the access network device 102 supports a network slice corresponding to the session of the access network device 104. In reality, the access network device 101 sends an automatic change request to the access network device 102 , but some sessions usually cannot be automatically switched to the access network device 102. There are many reasons why a session cannot be automatically switched to the access network device 102. For example, a radio feature on the access device access network 102 is not available (radio resource not available) or a requested network slice is not supported. However, in an existing solution, the access network device 101 cannot determine a reason why the session cannot be automatically switched to the access network device 102. If a resource for a first network slice corresponding to the requested session on the access network device 102 is not available, the access network device 101 still sends the automatic change request to the access network device 102 when another session needs to be changed automatically at the first network slice, and a case in that the session cannot be automatically switched to the access network device 102 still occurs. This reduces an automatic switching success rate.

[0107] In this embodiment of the present invention, after the access network device 101 sends the automatic change request to the access network device 102, the access network device 101 can obtain cause information for a session, which is rejected due to a network slice of the access network device 102, to help provide information for another session that needs to be requested to be automatically switched to the access network device 102. When a session corresponding to the same network slice needs to be changed automatically from the access network device 101, the access network device 101 can directly determine whether the session can be automatically switched to access network device 102, thereby increasing a success rate of automatic change. The access network device 101 can further select a better target base station for another terminal device to be automatically switched to automatic switching.

[0108] It should be noted that an example in which the

Petition 870190095647, of 09/24/2019, p. 108/212

28/94 access network is a base station is used for the description in the modalities of this application. In any embodiment of this request, in an optional manner, information about a supported network slice of a base station can include an identifier for at least one cell of the base station and indication information for at least one corresponding network slice. to each cell identifier. A base station can cover one or more cells. Each cell is indicated by using a cell identifier, and each cell can support one or more network slices. Each cell supports a different network slice and that cell identifier can match indication information for at least one network slice. For example, a specific form of representation is shown below (a name is just an example, and the name is not limited in the modalities of this application). A cell ID represents a cell identifier, an SNSSAI list represents indication information for a network slice, and a cell ID can correspond to at least one S-NSSAI list.

»> Cell ID»> S-NSSAI List [0109] Alternatively, in another optional way, information about a supported network slice of a base station can include information about the base station and indication information for at least one network slice corresponding to the base station. Each base station can support one or more network slices and therefore information about a base station can correspond to indication information for at least one network slice. For example, a specific form of representation is shown below (a name is just an example, and the name is not limited in the modalities of this application). A gNB ID represents information about the base station, an S-NSSAI list represents the indication information for a network slice, and a gNB ID can correspond to at least one SNSSAI list.

»> GNB ID»> S-NSSAI List [0110] Alternatively, in another optional way, information about a supported network slice from a base station can include information indicating at least one network slice corresponding to

Petition 870190095647, of 09/24/2019, p. 109/212

29/94 a tracking area (tracking area, TA) or a registration area (registration area, RA) to which a base station cell belongs. Each TA / RA can support one or more network slices and therefore information about a TA / RA can correspond to the indication information of at least one network slice. For example, a specific form of representation is shown below (a name is just an example, and the name is not limited in the modalities of this application). A tracking area identity / identifier, TAI, a registration area identity (RAI), a tracking area code (TAC), or a registration area identity / identifier, RAC are used to represent information about a TA / RA, an SNSSAI list represents the indication information for a network slice, and a TAI / RAI / TAC / RAC can correspond to at least one S-NSSAI list.

»> TAI / RAI / TAC / RAC»> List S-NSSAI [0111] Information about the base station in any form of this application can include at least one base station of a base station identity, a unit identity base station central (central unity ID), a base station distributed unit identity (distributed unit ID), a physical base cell cell identifier (PCI), and a global base cell identity base station (Cell Global ID, CGI).

[0112] It should also be noted that, the indication information of each network slice in any modality of this order can include at least one identifier of a network slice, single network slice selection assistance information assistance information, S-NSSAI), and RAN network slice selection assistance information, R-NSSAI.

[0113] The network slice identifier can be represented by using at least one of the following (1) to (7):

[0114] (1) Network slice type information. For example, network slice type information may indicate a type of network slice such as enhanced mobile broadband (eMBB) service, ultra-reliable, low-latency communications (Ultra

Petition 870190095647, of 09/24/2019, p. 110/212

30/94

Reliable Low Latency Communications, URLLC), or massive machine type communications (mMTC). Optionally, the network slice type information can indicate a type of end-to-end network slice, including a type of RAN main network slice (Core Network, CN), or it can indicate a type of RAN side network slice or a type of CN side network slice.

[0115] (2) Type of service information related to a specific service. For example, service type information may indicate a service feature such as a video service, a vehicle internet service, or a voice service, or information about a specific service.

[0116] (3) Tenant information (Tenant), used to instruct to create or rent customer information from the network slice, such as Tencent or State Grid.

[0117] (4) User group information, used to instruct the grouping of users based on a characteristic such as a user level.

[0118] Slice group information (5), used to instruct the grouping of network slices based on a characteristic. For example, the feature includes that all network slices that can be accessed by the terminal device can be used as a group of slices. Or, a group of network slices can be determined according to another criterion.

[0119] (6) Example information for network slices, used to indicate an identifier and characteristic information for an example created for the network slice. For example, an identifier indicating a sample network slice can be allocated to the sample network slice, or a new identifier can be mapped based on a sample network slice identifier and is associated with the sample network slice. network. A receiving side can identify, based on the identifier, the specific network slice example indicated by the identifier.

[0120] (7) Dedicated Core Network, DCN, dedicated main network identifier. The identifier is used to uniquely indicate a dedicated core network in a Long Term Evolution (LTE) system or an enhanced LTE system (enhanced LTE, eLTE), for example, a dedicated core network on the Internet of Things. Optionally, the

Petition 870190095647, of 09/24/2019, p. 111/212

31/94 mapping can be performed on the DCN identifier and the network slice identifier, the DCN identifier can be mapped to the network slice identifier, and the network slice identifier can also be mapped to the DCN identifier.

[0121] The S-NSSAI includes at least slice type / service type information (Slice / Service Type, SST), and optionally, it can additionally include slice differentiator information (Slice Differentiator, SD). SST information is used to indicate the behavior of a network slice, for example, a characteristic and service type of the network slice. SD information is complementary to SST information. If the SST indicates the implementation of a plurality of network slices, the SD can correspond to a unique example of a network slice.

[0122] The R-NSSAI represents a specific S-NSSAI set, that is, an identifier of a specific S-NSSAI set.

[0123] It should be understood that, in the modalities of this request, the information of indication of a network slice can be represented by using at least one of the previous parameters. For example, network slice indication information can be represented by using a type of network slice, or can be represented by using a type of network slice and a type of service, or can be represented by using a type of service and tenant information. This is not limited to the modalities of this application. How the network slice indication information is represented is not described in the details below. Optionally, a specific encoding format of the network slice indication information is not limited. Different fields that can be carried in an interface message between different devices represent indication information for different network slices or can be replaced with abstract index values, and different index values correspond to different network slices. Certainly, another identifier can be included in addition to the previous identifiers, and this is not limited here. It should be understood that if the terminal device, the access network device, or the main network device supports a plurality of network slices, the indication information of a supported network slice of the terminal device, the network device of access, or the primary network device can be represented in a form of

Petition 870190095647, of 09/24/2019, p. 112/212

32/94 list of previous, at least one identifier.

[0124] It should be noted that "there is a communications interface" or "there is an interface" in the modalities of the present invention indicate that a communications interface is established and that the communications interface is available (available); and that “there is no communications interface” or “there is no interface” indicates that no communications interface is established or an established communications interface is not available (unavailable!). The communications interface is not limited in this report as a communications interface between access network devices and a communications interface between the access network device and the primary network device.

[0125] The modalities of the present invention can be applied to another communication system that supports a network slice. The terms "system" and "network" can be interchanged. A system architecture described in the embodiments of the present invention is intended to describe the technical solutions in the embodiments of the present invention more clearly, and does not constitute any limitation whatsoever in the technical solutions provided in the embodiments of the present invention. A technician with common skill in the art may know that, with the evolution of the system architecture, the technical solutions provided in the modalities of the present invention are also applicable to similar technical problems.

[0126] With reference to FIGURE 3, FIGURE 3 shows a method of communication according to an embodiment of the present invention. In this embodiment, an example where an access network device is a base station is used for the description. As shown in FIGURE 3, the method of communication refers to a terminal device, a source base station, a target base station and a main network device. FIGURE 3 corresponds to a communication method used when the target base station determines that the automatic switch was successful. The source base station is a base station that currently establishes a communication connection with the terminal device, and the target base station is a base station from which a session of the terminal device is requested to be switched automatically.

[0127] As shown in FIGURE 3, the communication method includes

Petition 870190095647, of 09/24/2019, p. 113/212

33/94 to step 301 to step 307. For details, see the following specific descriptions.

[0128] 301. The source base station sends an automatic change request to the target base station.

[0129] There is a communications interface such as an Xn interface between the source base station and the target base station. In this case, the source base station and the target base station can communicate with each other. The automatic change request is used to request the automatic change of the session from the terminal device from the source base station to the target base station. The automatic change request includes an identifier for a session requested to be changed automatically and the indication information for a network slice corresponding to the session. For example, if there is a plurality of sessions selected to be changed automatically, the automatic change request carries the indication information for a network slice corresponding to each session. Correspondingly, the target base station receives the automatic change request.

[0130] Optionally, the session requested to be changed automatically can be an activated terminal device session, and can be understood as a session currently being performed on the terminal device. For example, the terminal device session includes an A1 session, an A2 session, an A3 session, an A4 session and an A5 session. Session A1, session A2 and session A3, are in an active state, and session A4 and session A5 are in a disabled state. In this case, the automatic change request includes session identifier A1, session identifier A2, session identifier A3, the network slice indication information corresponding to session A1, network slice indication information corresponding to session A2, and network slice indication information corresponding to session A3. A deactivated session does not need to be automatically switched to the target base station and therefore signal transmission can be reduced.

[0131] Optionally, before sending the automatic change request, the source base station can further determine, based on information obtained about a supported network slice from the target base station

Petition 870190095647, of 09/24/2019, p. 114/212

34/94 and in the network slice indication information obtained corresponding to the requested session to be automatically changed, a specific session that is in the requested session to be automatically changed and whose corresponding network slice is supported by the target base station and a session that is in the requested session to be changed automatically and whose network slice is not supported by the target base station. In addition, if the network slices corresponding to all sessions requested to be automatically changed are not supported by the target base station, the source base station may not send the automatic change request to the target base station.

[0132] Optionally, the session requested to be changed automatically can be a first session and a second session of the terminal device. A network slice corresponding to the first session is supported by the target base station, and a network slice corresponding to the second session is not supported by the target base station. Since there is a communications interface between the source base station and the target base station, the source base station can determine, by interacting with the target base station, another base station, a side of the main network or the like, the supported network slice of the target base station. In addition, the source base station can classify, based on the indication of the network slice indication corresponding to each session requested to be changed automatically and the supported network slice of the target base station, the sessions requested to be changed automatically, to get the first session and the second session. For example, the sessions requested to be switched automatically include a B1 session, a B2 session and a B3 session, the target base station supports network slices corresponding to the B1 session and the B2 session, but the target base station does not support a network slice corresponding to session B3. In this case, the identifiers of the sessions requested to be changed automatically are classified into two types and are sent to the target base station. One type is an identifier of the first session, and the other type is an identifier of the second session. Therefore, the target base station can directly determine a session that is not supported by the target base station, thereby improving the effectiveness of determining an automatic change response message.

Petition 870190095647, of 09/24/2019, p. 115/212

35/94

Certainly, special classification processing may not be performed for all sessions that need to be changed automatically.

[0133] Optionally, the session requested to be changed automatically can be a first session of the terminal device, and a network slice corresponding to the first session is supported by the target base station. Therefore, for sessions corresponding to the network slices that are not supported by the target base station, the target base station does not need to determine whether a network slice corresponding to the session requested to be changed automatically is supported and can directly determine, with based on a resource usage state of a network slice from the target base station, whether to automatically switch the first session. In this case, the target base station does not need to perform admission control in a second session, thereby saving processing time to perform admission control in the second session.

[0134] Optionally, the source base station selects one from a plurality of base stations that have a communications interface with the source base station as the target base station. In addition, the target target base station supports network slices corresponding to all or some selected sessions to be automatically switched, so that an automatic change failure caused because the target base station does not support network slices from all selected sessions to be changed automatically are avoided. A number of automatic switching failures are reduced to increase the automatic switching success rate.

[0135] Optionally, if the source base station receives a measurement report sent by the terminal device, the source base station can select the target base station based on the measurement report, and perform step 301 to send the request for automatic switching to the target base station. The measurement report includes a measurement report value of at least one of a cell and a base station. Optionally, if the measurement report includes a cell measurement report value, the included cell can be a cell from the source base station or a cell from another base station. If the measurement report includes a base station measurement report value, the included base station may be the

Petition 870190095647, of 09/24/2019, p. 116/212

36/94 source base station or other base station. Optionally, a number of cells and a number of base stations included in the measurement report are not limited in this embodiment of the present invention.

[0136] 302. The target base station performs admission control based on a factor such as a network slice support state, a resource usage state or an automatic change request.

[0137] The target base station performs admission control if the target base station receives the automatic change request sent by the source base station. Optionally, the target base station determines an automatic change response message based on a factor such as the network slice indication information corresponding to each session in the automatic change request, a support state of the target base station or a resource usage state.

[0138] For example, for a B4 session, if the information about the supported network slice of the target base station includes indication information for a network slice corresponding to the B4 session, this indicates that the target base station supports the slice corresponding to session B4. If the information about the supported network slice of the target base station does not include the indication information of the network slice corresponding to the B4 session, this indicates that the target base station does not support the network slice corresponding to the B4 session. In this case, session B4 is a rejected session. In addition, when the target base station supports the network slice corresponding to session B4, if the target base station can still allocate a resource for the network slice corresponding to session B4, the target base station determines that session B4 it is an accepted session. If the target base station cannot allocate a resource for the network slice corresponding to session B4, the target base station determines that session B4 is a rejected session. In this way, the target base station can determine the automatic change response message via admission control.

[0139] Optionally, even if only the first session is carried in step 301, the target base station can check the network slice indication information corresponding to the first session (one or more sessions) to determine whether the corresponding network slice the first session is currently supported.

Petition 870190095647, of 09/24/2019, p. 117/212

37/94 [0140] In addition, the automatic change response message can be an automatic change request confirmation message, or the automatic change response message is an automatic change failure message. In the embodiment shown in FIGURE 3, a case is described in which the automatic change response message is an automatic change request confirmation message. In this case, the session requested to be changed automatically includes a session that can be automatically changed to the target base station and a session that is rejected by the target base station. The session can be rejected by the target base station because the target base station does not support a network slice corresponding to the rejected session, or because a resource for the network slice, corresponding to the rejected session, from the target base station is not available . Therefore, the automatic change request confirmation message includes rejection indication information, and rejection indication information is used to indicate cause information corresponding to a session, which is rejected by the target base station due to a slice of network, from the requested session to be automatically changed. The cause information is: the target base station does not support the network slice corresponding to the rejected session, or a resource is not available for a network slice being supported by the target base station and corresponding to the rejected session.

[0141] Optionally, the cause information in this modality of the present invention can be indicated by using an information element (information element, IE), an indicator (flag), a cause value (cause) or similar, and this does not is limited in this embodiment of the present invention.

[0142] For example, if the session requested to be changed automatically includes the first session and the second session, the cause information for the rejected session can be: the target base station does not support the network slice corresponding to the rejected session, or a resource is not available for a network slice being supported by the target base station and corresponding to the rejected session. If the session requested to be changed automatically includes the first session, the cause information for the rejected base station session is: the resource is not available for the network slice, where the network slice corresponds to the rejected session. If the

Petition 870190095647, of 09/24/2019, p. 118/212

38/94 first session includes a plurality of data streams and at least one data stream from the first session is admitted (admitted) by the target base station and at least one data stream is rejected by the target base station, indication information indicating a reason for rejecting at least one data stream from the first session can be carried. For example, the reason includes: a resource that is not available or a resource for the network slice corresponding to the first session that is not available at the target base station. The data flow is either a traffic flow or a QoS flow (QoS flow).

[0143] 303. The target base station sends an automatic change request confirmation message to the source base station.

[0144] The automatic change request confirmation message includes an accepted session identifier, a rejected session identifier, and cause information corresponding to the rejected session. For example, the automatic change request confirmation message can be an automatic change confirmation or an automatic change request confirmation.

[0145] For example, with reference to Table 1, Table 1 is a PDU session release list or a PDU session rejection list. The rejected session identifier and the cause information corresponding to the rejected session that are included in the automatic change request confirmation message can be represented in Table 1.

Table 1

PDU Session Release List / PDU Session Reject List (Release List for PDU Sessions / PDU Session List Not Accepted)> PDU Session Identifier (PDU Session ID)> Cause Value (Cause) [0146] Optionally, the automatic change request confirmation message additionally includes retransmission indication information corresponding to the rejected session. The retransmission indication information is used to indicate whether the terminal device has

Petition 870190095647, of 09/24/2019, p. 119/212

39/94 permission to route, to a supported network slice from the target base station, a rejected session data stream. For example, the rejected session is session B1 and session B1 corresponds to a network slice 1. The cause information for the rejected session B1 can be: the target base station does not support network slice 1 corresponding to session B1, or the target base station supports network slice 1 but a feature for network slice 1 is not available. Regardless of a reason for the rejection of session B1, if the target base station supports a network slice 2, and a data stream from session B1 is routed to network slice 2, data transmission can also be implemented. In this case, the target base station determines what retransmission indication information corresponding to session B1 is: the terminal device is allowed to route the data stream of session B1 to network slice 2 supported by the target base station. It can be understood that, the retransmission indication information may not indicate a specific network slice to which the data stream is routed. In addition, if a network slice to which the data stream of session B1 can be routed does not exist at the target base station, or the target base station cannot meet a QoS requirement of the data stream of session B1 , the target base station determines that the retransmission indication information corresponding to session B1 is: the terminal device is not allowed to route the data stream from session B1 to the supported network slice of the target base station. It can be understood that the relay indication information and the cause information can be identified by using an IE / indicator / cause value. The IE / indicator / cause value indicates a cause of rejection for a session and also indicates that a stream of data corresponding to the rejected session can be routed to another network slice. For specificity, a session can be reestablished on another supported network slice of the target base station to transmit the data stream. Relay indication information and cause information can be identified using two different ES / indicators / cause values.

[0147] Optionally, the automatic change request confirmation message additionally includes an identifier of a rejected holder or an identifier of a rejected data stream of the requested session to be changed automatically. A session includes a plurality of flows

Petition 870190095647, of 09/24/2019, p. 120/212

40/94 of data. A carrier can correspond to a plurality of data streams. A rejected holder can be a holder included in an accepted session or it can be a holder included in a rejected session. A rejected data stream can be an accepted session data stream or it can be a rejected session data stream. For example, at least one accepted session holder is a rejected holder, and at least one accepted session data stream is a rejected data stream. A rejected carrier or rejected data stream is sent to the source base station using the automatic change request confirmation message, so that the source base station can recognize the rejected carrier or the rejected data stream.

[0148] For example, if the automatic change request confirmation message additionally includes the rejected data stream identifier, with reference to Table 2, Table 2 includes the accepted session identifier, rejected data stream cause information , and the rejected data stream identifier. A list of accepted sessions can be represented as a PDU Session Admitted List or a PDU Sessions Subject to Forwarding List.

Table 2

List of accepted sessions> PDU session identifier (PDU Session ID)> Cause value (Cause)> Identifier / identifier list of a rejected data flow (traffic flow ID / QoS (list)) [0149] For example , the previous information included in the automatic change request confirmation message can be returned in a list form. The session requested by the source base station to be changed automatically includes the first session and the second session, and the automatic change response message is determined as the automatic change request confirmation message. An example where the first session includes a C1 session, a C2 session and a C3 session, and the second session includes a D1 session and a D2 session is used

Petition 870190095647, of 09/24/2019, p. 121/212

41/94 for the description. The session that is accepted by the target base station includes session C1 and session C2, and the session that is rejected by the target base station includes session C3, session D1 and session D2. The target base station supports a network slice corresponding to the C3 session, but the automatic switching failures because a resource for the network slice is not available. At least one carrier or data stream from the accepted C1 session is rejected.

[0150] In this case, with reference to Table 3, Table 3 is a form of list of accepted sessions according to one embodiment of the present invention. Cause information corresponding to session C1 including the rejected carrier / data stream can be included in the automatic change request confirmation message. Cause information is used to indicate cause information for at least one rejected carrier or at least one rejected data stream. For example, the R3 cause information for at least one rejected carrier or at least one rejected data stream may be unavailable resources, an invalid QoS combination corresponding to a session data stream, an multiple data stream or the like. The retransmission indication information corresponding to the C1 session including the rejected carrier / data stream can also be included in the automatic change request confirmation message. One meaning represented by the retransmission indication information is the same as the previous content. The retransmission indication information Y indicates that the terminal device is allowed to route the rejected data stream from session C1 to the supported network slice of the target base station. Therefore, more accurate information can be provided for the next automatic change. An automatic change success rate is increased. A rejected carrier / data stream identifier, retransmission indication information, and cause information can be optionally carried in the automatic change request confirmation message. A list of recognized sessions can be represented as a PDU Session Admitted List or a PDU Sessions Subject to Forwarding List.

Table 3

Petition 870190095647, of 09/24/2019, p. 122/212

42/94

List of accepted sessions Session identifier Rejected carrier / data stream identifier Cause information Relay indication information Session C1 Identifier of at least one rejected carrier / data stream R3 Y Session C2 Null (indicating that the identifiers of all QoS carriers / flows are accepted) Null Null

[0151] Furthermore, with reference to Table 4, Table 4 is a form of list of rejected sessions according to one embodiment of the present invention. The rejected carrier / data stream identifier and retransmission indication information can optionally be carried in the automatic change request confirmation message. The cause information for the C3 session is R1, indicating that the target base station supports a network slice corresponding to the C3 session but a resource for the network slice is not available. The cause information for session D1 and the cause information for session D2 are R2, indicating that the target base station does not support a network slice corresponding to session D1 or a network slice corresponding to session D2. Y in the retransmission indication information indicates that the terminal device is allowed to route a data stream from the C3 session to the supported network slice of the target base station. N in the retransmission indication information indicates that the terminal device is not allowed to route data streams from the

Petition 870190095647, of 09/24/2019, p. 123/212

43/94 session D1 and session D2 for the supported network slice of the target base station. A list of rejected sessions can be represented as a PDU session release list (PDU Sessions to Release List) or a PDU session rejection list (PDU Sessions Not Admitted List).

Table 4

Session identifier Rejected carrier / data stream identifier Cause information Relay indication information List of Session C3 Identifiers for all carriers / data streams of the C3 session R1 Y rejected sessions Session D1 Identifiers for all carriers / data streams of the D1 session R2 N Session D2 Identifiers for all carriers / data flows of the D2 session R2 N

0152] In addition, it can be seen that in Table 4, the list is generated based on each session identifier. In another optional way, the list can be generated based on the cause information. As shown in Table 5, Table 5 is another form of list of sessions that are rejected according to one embodiment of the present invention. In this case, part of the cause information corresponds to a plurality of session identifiers, thereby reducing signaling transmission. The rejected carrier / data stream identifier and retransmission indication information can be optionally carried in the

Petition 870190095647, of 09/24/2019, p. 124/212

44/94 confirmation of automatic change request. A list of rejected sessions can be represented as a PDU session release list (PDU Sessions to Release List) or a PDU session rejection list (PDU Sessions Not Admitted List).

Table 5

List of rejected sessions Cause information Session identifier Rejected carrier / data stream identifier Relay indication information R1 Session C3 Identifiers for all C3 session data carriers / streams Y R2 Session D1 Identifiers of all carriers / data streams of session D1 N Session D2 Identifiers of all carriers / data streams of the D2 session N [0 ' 53] Optionally, the message request confirmation message

Automatic changeover still carries carrier configuration information determined by the target base station, and carrier configuration information is used to instruct the terminal device to perform carrier configuration based on the configuration information.

[0154] In addition, optionally, the automatic change request confirmation message additionally includes complete automatic change indication information. The informations

Petition 870190095647, of 09/24/2019, p. 125/212

Complete configuration change indication 45/94 are used to indicate that the terminal device does not need to modify each original carrier. The automatic change of complete configuration can be accomplished by using carrier configuration information determined by the target base station. For specificity, all original carrier configurations are suppressed and carrier configuration information determined by the target base station is stored, to improve the effectiveness of carrier configuration. Optionally, if the automatic change request includes the complete automatic change indication information, the automatic change request confirmation message additionally includes the complete automatic change indication information.

[0155] Optionally, the automatic change request confirmation message additionally includes information about the supported network slice of the target base station. This helps the target base station notify the source base station of information about a network slice currently supported by the target base station, thereby reducing the interaction between the source base station and the target base station.

[0156] Correspondingly, the source base station receives the automatic change request confirmation message sent by the target base station.

[0157] 304. The source base station sends an automatic change command to the terminal device.

[0158] The source base station sends the automatic change command to the terminal device after the source base station receives the automatic change request confirmation message sent by the target base station. For example, the auto switch command can be an RRC connection reconfiguration message (RRC Conection Reconfiguration) or a handover command message. The automatic change command includes at least one of an accepted session identifier, an accepted stream data identifier, and a bearer identifier corresponding to the accepted session, in order to notify the terminal device of a session, a data stream, or a carrier that can be automatically switched to the station

Petition 870190095647, of 09/24/2019, p. 126/212

46/94 target base.

[0159] Optionally, the automatic change command additionally includes the session that is rejected by the target base station and the retransmission indication information corresponding to the rejected session. Thus, the terminal device determines, based on the retransmission indication information corresponding to the rejected session, whether to initiate a session definition request for the target base station of the rejected session. Optionally, for a plurality of rejected sessions, the automatic change command can include retransmission indication information corresponding to each session, or the automatic change command can indicate allowed retransmission and not allowed retransmission. This is not limited in this embodiment of the present invention.

[0160] Optionally, if the automatic change request confirmation message includes carrier configuration information determined by the target base station, the automatic change command additionally includes the carrier configuration information determined by the target base station, to instruct the terminal device to perform carrier configuration based on configuration information. If the automatic change request confirmation message additionally includes complete automatic configuration change indication information, the automatic change command additionally includes complete automatic configuration change indication information, to improve the effectiveness of bearer configuration.

[0161] Correspondingly, the terminal device receives the automatic change command sent by the source base station.

[0162] 305. The terminal device sends an automatic change confirmation message to the target base station.

[0163] For example, the automatic change confirmation message can be a complete handover command message, or it can be a complete RRC connection reconfiguration message.

[0164] Optionally, after the terminal device receives the automatic change command, random access is performed between the terminal device and the target base station, to return a message of

Petition 870190095647, of 09/24/2019, p. 127/212

47/94 confirmation of automatic change to the target base station. The automatic change confirmation message is used to indicate that the terminal device has completed the automatic change.

[0165] 306. The target base station sends a path switching request to the main network device.

[0166] The target base station sends the path switching request to the main network device when it receives the automatic change confirmation message. For example, the path switching request is a path switching request. The trajectory switch request includes the session identifier that is accepted by the target base station, so that the main network device performs the path switch in the accepted session.

[0167] Optionally, the trajectory switching request can additionally include the session identifier that is rejected by the target base station, so that the main network device releases or deactivates the rejected session.

[0168] In addition, there is a service enabled and a service disabled on the terminal device, and the main network device stores all sessions on the terminal device. Both the accepted session and the rejected session belong to the activated service. The identifiers of such two sessions are carried in the path switching request, so that the main network device can determine a disabled session from all the stored sessions of the terminal device. In this way, the main network device does not have to deal with such sessions, and only needs to deal with the accepted session and the rejected session, thereby improving processing efficiency.

[0169] Optionally, the path switching request additionally includes information for indicating the network slice corresponding to the session that is rejected by the target base station, so that the main network device can compare the network slice corresponding to the rejected session with a network slice that is supported by a target base station and that is stored on the main network device. Therefore, the main network device can obtain, if the session is rejected because the target base station does not support the network slice. If yes, the primary network device

Petition 870190095647, of 09/24/2019, p. 128/212

48/94 subsequently triggers a session release (remove) process, to reduce the storage space occupied by such sessions on the primary network device. If not, the primary network device can subsequently trigger a session deactivate process, so that the primary network device can quickly resume the session when the session needs to be activated.

[0170] Optionally, the request to switch the trajectory includes the cause information corresponding to the session that is rejected by the target base station. Cause information is carried over, so that the main network device can perform different processing in sessions that are rejected for different causes.

[0171] Correspondingly, the main network device receives the path switching request sent by the target base station.

[0172] 307. The main network device switches the trajectory in an accepted session, and deactivates or releases a rejected session.

[0173] The fact that the main network device performs the path switching in the accepted session is specifically:

[0174] The fact that the main network device performs the deactivation processing in the rejected session is specifically suspending the rejected session. A context corresponding to the session can be stored on the primary network device, so that the primary network device can quickly resume the session when the session needs to be activated.

[0175] The fact that the main network device releases the rejected session is specifically: the main network device releases a context corresponding to the session. For example, an AMF network element instructs an SMF network element to carry out the context corresponding to the session, thereby reducing the storage space occupied by such sessions on the primary network device.

[0176] Optionally, the main network device can perform deactivation in the rejected session because a network slice feature of the target base station is not available, so the session data transmission can be resumed when the network slice the target base station is

Petition 870190095647, of 09/24/2019, p. 129/212

49/94 available. In comparison with the release performed in the session, the time required for the activation processing is less, by reestablishing the session when the network slice of the target base station is not limited, so that the data transmission of a deactivated session can be more quickly resumed.

[0177] Optionally, the main network device can perform the release of the session which is rejected because the target base station does not support the network slice. The supported network slice of the target base station does not change in a short time, and therefore the session data transmission cannot be resumed in a short time. In this case, if the deactivation processing is performed in the session, more storage space on the primary network device will be occupied, and the storage space will be wasted.

[0178] 308. The main network device sends a path switching request response message to the target base station.

[0179] The main network device sends the path switching request response message to the target base station. The path switching request response message includes an identifier for a session for which path switching was completed successfully. For example, the path switching request response message is either the path switching request acknowledgment or a path switching request response.

[0180] Optionally, the path switching request response message additionally includes a session identifier for the path switching failure, so that the target base station determines a path switching result from the primary network device .

[0181] In this embodiment of the present invention, after the source base station sends the automatic change request to the target base station, the source base station can obtain the cause information for the session, which is rejected due to the slice of target base station network, to help provide information for another session that needs to be requested to be automatically switched to the target base station. When a session corresponding to the same network slice needs to be changed automatically from the source base station, the source base station can determine

Petition 870190095647, of 09/24/2019, p. 130/212

50/94 directly if the session can be automatically switched to the target base station, thereby increasing an automatic switching success rate.

[0182] With reference to FIGURE 4, FIGURE 4 shows a method of communication according to an embodiment of the present invention. In this embodiment, an example in which an access network device is a base station is used for the description. As shown in FIGURE 4, the method of communication refers to a terminal device, a source base station, and a target base station. FIGURE 4 corresponds to a communication method used when the target base station determines that automatic switching fails. The source base station is a base station that currently establishes a communication connection with the terminal device, and the target base station is a base station to which a session of the terminal device is requested to be switched automatically.

[0183] As shown in FIGURE 4, the communication method includes steps 401 to step 404. For details, see the following specific descriptions.

[0184] 401. The source base station sends an automatic change request to the target base station.

[0185] For step 401, refer to the corresponding detailed descriptions of step 301 in the mode shown in FIGURE 3. The details are not described in this report again.

[0186] 402. The target base station performs admission control based on a factor such as a network slice support state, a resource usage state or an automatic change request.

[0187] The target base station performs admission control if the target base station receives the automatic change request sent by the source base station. Optionally, the target base station determines an automatic change response message based on a factor such as indication information for a corresponding network slice for each session in the automatic change request, a support state for a network slice of the network. target base station, or a resource usage state.

[0188] In addition, the automatic change response message

Petition 870190095647, of 09/24/2019, p. 131/212

51/94 can be an automatic change request confirmation message, or the automatic change response message is an automatic change failure message. In the embodiment shown in FIGURE 4, a case is described in which the automatic change response message is an automatic change failure message. In this case, none of the sessions requested to be switched automatically can be switched automatically to the target base station. That is, the sessions requested to be automatically changed at all, are sessions rejected by the target base station. Automatic session switching can be rejected by the target base station because the target base station does not support a network slice corresponding to the rejected session, or because a resource for the network slice, corresponding to the rejected session, from the target base station Not Available. Therefore, the automatic change request confirmation message includes rejection indication information. Reject indication information is used to indicate cause information corresponding to a session, which is rejected by the target base station due to a network slice, from the requested session to be changed automatically. The cause information is: the target base station does not support the network slice corresponding to the rejected session, or a resource is not available for a network slice being supported by the target base station and corresponding to the rejected session.

[0189] Optionally, the cause information in this embodiment of the present invention can be indicated by using an IE, an indicator, a cause or the like. This is not limited in this embodiment of the present invention.

[0190] For example, if the session requested to be changed automatically includes a first session and a second session, the cause information for the rejected session can be: the target base station does not support the network slice corresponding to the rejected session, or the feature is not available for a network slice being supported by the target base station and corresponding to the rejected session. If the session requested to be changed automatically includes a first session, the cause information for the rejected session is: the resource is not available for the network slice corresponding to the rejected session.

[0191] 403. The target base station sends a fault message from

Petition 870190095647, of 09/24/2019, p. 132/212

52/94 automatic switch to the source base station.

[0192] The automatic change failure message includes the cause information corresponding to the rejected session. For example, the automatic change failure message is a handover preparation failure message.

[0193] Optionally, the automatic change failure message additionally includes an identifier of a rejected carrier or an identifier of a rejected data stream of the requested session to be changed automatically. A session includes a plurality of data streams, and a carrier corresponds to at least one data stream. The rejected carrier can be a rejected session carrier, and the rejected data stream can be a rejected session data stream. For example, all holders of the rejected session are rejected holders, and all data flows from the rejected session are rejected data flows. The rejected carrier ID or rejected data stream is sent to the source base station using the automatic change failure message, so that the source base station can recognize the rejected carrier or the rejected data stream.

[0194] Furthermore, in this embodiment of the present invention, the automatic change failure message can be represented by using a rejected session list. For the list, consult all the contents in table 4 and Table 5, except for the indication of retransmission. The rejected carrier / data stream identifier is the optional content of the automatic change failure message, and this is not limited in this embodiment of the present invention.

[0195] Optionally, if the automatic change response message is an automatic change failure message, the rejection indication information can be used to indicate that the target base station does not support a network slice corresponding to any session of the terminal device. For example, if the session requested to be switched automatically includes the first session and the second session, and the source base station does not know about a supported network slice recently updated by the target base station, it is likely that the target base station will not support any requested session. In this case, in an optional solution, the message

Petition 870190095647, of 09/24/2019, p. 133/212

Automatic change failure 53/94 includes the rejection indication information (indicated by an IE, an indicator, a cause or the like) and a rejected session identifier. For example, in this case, with reference to Table 6, the PDU session release list includes an automatic change rejection indication value. In another optional solution, the automatic change failure message includes the rejection indication information (indicated by an IE, an indicator, a cause or the like). In this case, the PDU session release list in table 6 does not need to be carried, and only an automatic change failure value is carried. In this way, the source base station determines a network slice that is not supported by the target base station.

Table 6

PDU Session to Release List

Indication value (Indicator) [0196] Alternatively, the rejection indication information can be used to indicate that the target base station supports a network slice corresponding to any session included in the automatic change request, and that the base station target refuses to automatically change all sessions included in the automatic change request. For example, if the session requested to be changed automatically includes the first session, and a resource for a network slice from a corresponding target base station for each session requested to be changed automatically is not available, in an optional solution, the message automatic shift failure includes rejection indication information (indicated by an IE, an indicator, a cause or the like); in another optional solution, the automatic change failure message includes the rejection indication information (indicated by an IE, an indicator, a cause or the like) and the rejected session identifier, so that the source base station determines a resource usage state of a network slice, corresponding to the session requested to be changed automatically, from the target base station.

[0197] Alternatively, the rejection indication information can be used to indicate that the target base station supports a network slice corresponding to a third session but does not refuse to change

Petition 870190095647, of 09/24/2019, p. 134/212

54/94 automatically the third session, and that the target base station does not support a network slice corresponding to a fourth session. The session requested to be changed automatically includes the third session and the fourth session. For example, when the source base station does not determine a recently supported supported network slice by the target base station, if the session requested by the source base station to be changed automatically includes the first session and the second session, or if the session requested by the source base station to be changed automatically includes the first session, the target base station can reclassify, based on the support state and resource usage state of the target base station's network slice, the sessions requested for be changed automatically. For specificity, the source base station determines that the first session supported by the target base station can switch to a session that is not supported by the target base station, and the source base station determines that the second session that is not supported by the target base station can switch to a session that is supported by the target base station. Therefore, the third session in the rejection indication information resumed by the target base station can be the same or different from the first session in the automatic change request, and the fourth session in the rejection indication information returned by the target base station can be be the same or different from the second session on the automatic change request. In addition, in this case, the target base station can classify the sessions corresponding to the same cause of automatic change rejection in a session type and establish a correspondence between those session types and a part of the rejection indication information (indicated by an IE, an indicator, a cause or the like). That is, the automatic change failure message includes two pieces of rejection indication information and session identifiers corresponding to two pieces of rejection indication information. Alternatively, the target base station can establish a match between each rejected session and a piece of rejection indication information (indicated by an IE, an indicator, a cause or the like). That is, the automatic change failure message includes an identifier for at least one rejected session and corresponding rejection indication information for each rejected session. Alternatively, the automatic change failure message includes

Petition 870190095647, of 09/24/2019, p. 135/212

55/94 two pieces of rejection indication information. This is not limited in this embodiment of the present invention. Optionally, for a rejected session, due to a feature for a target base station network slice not being available, the rejected session identifier and the network slice indication information corresponding to the rejected session can be added to the failure message automatic changeover, to indicate to the source base station that a resource for that network slice from the target base station is not available without the use of additional indication information. In this way, the source base station can determine a resource usage state of a network slice at the target base station.

[0198] Alternatively, the rejection indication information can be used to indicate that the target base station refuses to automatically change a session. For example, when the session requested by the source base station to be changed automatically includes the first session and the second session, a resource for each network slice supported by the target base station is not available. In this case, the automatic change failure message includes a piece of rejection indication information, indicating that the target base station not only rejects the session requested to be changed automatically, but also rejects the automatic change from one session corresponding to another supported network slice. In this way, the source base station can obtain the resource usage status of all network slices at the target base station in a short time. This provides information to be switched automatically from another session at the source base station, thereby increasing an automatic switching success rate.

[0199] Optionally, the automatic change failure message additionally includes information about the supported network slice of the target base station. This helps the target base station notify the source base station of information about a network slice currently supported by the target base station, thereby reducing the interaction between the source base station and the target base station.

[0200] 404. The source base station sends an RRC connection release message to the terminal device.

[0201] The source base station sends the

Petition 870190095647, of 09/24/2019, p. 136/212

56/94 RRC connection to the terminal device when it determines the automatic switching failure, so that the terminal device releases an RRC connection as soon as possible, to avoid subsequent radio link failure and reduce signaling overhead.

[0202] Optionally, the RRC connection release message includes indication information for a network slice supported by a neighboring cell of a source cell, indication information for a network slice supported by a TA / RA which the neighboring cell source cell belongs to, or information about a network slice supported by a base station neighboring the source base station. The source cell is a cell served by the terminal device when the source base station requests automatic switching to the target base station. In this way, the source base station obtains more network slices supported by another cell or another base station. This provides information for subsequent processing, and reduces interaction signaling for obtaining network slice information between a second base station and a base station neighboring a first base station, thereby improving the convenience of obtaining information about the supported network slice of the base station.

[0203] Correspondingly, the terminal device receives the RRC connection release message and releases an RRC connection.

[0204] In this embodiment of the present invention, after the source base station sends the automatic change request to the target base station, the source base station can obtain the cause information for the session, which is rejected due to the slice of target base station network, to help provide information for another session that needs to be requested to be automatically switched to the target base station. When a session corresponding to the same network slice needs to be changed automatically from the source base station, the source base station can directly determine whether the session can be automatically switched to the target base station, thereby increasing a rate of automatic switching success.

[0205] With reference to FIGURE 5, FIGURE 5 shows another method of communication in accordance with an embodiment of the present invention. An example where an access network device in the communication method

Petition 870190095647, of 09/24/2019, p. 137/212

57/94 is a base station is used for the description. As shown in FIGURE 5, the communication method refers to a first base station and a main network device. For details, refer to the following specific descriptions.

[0206] 501. The first base station sends a first message to the main network device. The first message is used to obtain indication information for a supported network slice from the primary network device to a PLMN.

[0207] The main network device can serve a plurality of public land mobile networks (Public Land Mobile Network, PLMN). Different PLMNs served by a primary network device can support different network slices. If different main network devices serve the same PLMN, the network slices supported by the different main network devices can be different. This is not limited in this embodiment of the present invention. For example, a first main network device can serve a first PLMN and a second PLMN. If the first main network device meets the first PLMN, the first main network device supports a network slice 1, a network slice 2 and a network slice 3. If the first main network device meets the second PLMN, the first primary network device will support network slice 1 and network slice 4. A second primary network device can serve the first PLMN. If the second main network device meets the first PLMN, the second main network device will support network slice 1, network slice 4 and a network slice 5.

[0208] Optionally, the first message carries an identifier from a PLMN and, therefore, the main network device resumes the indication information of a supported PLMN network slice indicated by the PLMN identifier served by the main network device. Optionally, the PLMN Identifier (PLMN ID) included in the first message can be part of the PLMN served from the first base station, or all PLMN served from the first base station.

[0209] Optionally, the first message does not carry an identifier for any PLMN and therefore the main network device can return supported network slice indication information for each PLMN

Petition 870190095647, of 09/24/2019, p. 138/212

58/94 served by the main network device. For example, if the primary network device serves three PLMNs, the primary network device sends a supported network slice indication information to the first base station for each PLMN served by the primary network device.

[0210] Correspondingly, the main network device receives the first message from the first base station.

[0211] 502. The main network device sends a second message to the first base station. The second message includes indication information for a supported network slice for a PLMN served by the main network device.

[0212] A supported network slice from the main network device to serve different PLMNs can be preconfigured by a network management device. For example, the network management device is operation, administration and maintenance (Operation Administration and Maintenance, OAM), and a supported network slice can be an updated network slice (for example, OAM performs an update to a main network , or performs an update due to another cause). This is not limited in this embodiment of the present invention.

[0213] The first base station receives the indication of the supported network slice for the PLMN served by the main network device, thereby helping to provide information when the first base station selects a main network device for the terminal device in order to more accurately select a primary network device for a terminal device session.

[0214] For example, the terminal device accesses the first PLMN, and a network slice corresponding to a session that needs to be served by the main network device is network slice 4. If the first main network device meets the first PLMN , the first main network device will support network slice 1, network slice 2 and network slice 3. If the first main network device serves the second PLMN, the first main network device will support network slice 1 and the network slice 4. If the second main network device serves the first PLMN, the second main network device will support network slice 1, network slice 4 and network slice 5. If a supported network slice the first primary network device is not

Petition 870190095647, of 09/24/2019, p. 139/212

59/94 returned with a PLMN granularity, the first main network device will support network slice 1, network slice 2, network slice 3 and network slice 4, and the second main network device will support network slice 1, network slice 4 and network slice 5. Therefore, it is very likely that the first base station will select the first main network device to serve the terminal device session. However, the first main network device does not support network slice 4 when the first main network device meets the first PLMN, and consequently, a selection error for a main network device occurs. However, if the supported network slice of the main network device is returned for each PLMN (in the PLMN granularity), a case in which the first base station selects the first main network device for the terminal device session can be avoided , and the accuracy of selecting a primary network device for the terminal device session can be improved.

[0215] Correspondingly, the first base station receives the second message sent by the main network device.

[0216] Optionally, if the first message carries an identifier from a PLMN, the main network device can send indication information of a supported network slice to the first base station to the PLMN (indicated by the PLMN identifier) serviced by the main network device; or the primary network device sends indication information of a supported network slice to all the PLMN (s) served by the primary network device to the first base station.

[0217] Optionally, if the first message does not carry an identifier from a PLMN, the main network device can return indication information of a supported network slice for each PLMN served by the main network device.

[0218] Optionally, there is no communications interface between the first base station and the main network device. For example, a communications interface between the first base station and the main network device is represented as N2 or NG. An N2 interface is used as an example. The first message sent by the first base station to the main network device can be an N2 interface setup request or an update message.

Petition 870190095647, of 09/24/2019, p. 140/212

60/94 base station configuration (for example, gNB configuration update). The first base station receives an N2 interface setup failure request message or a base station configuration update failure message (for example, gNB configuration update failure) from the device. main network. The main network device can send, using the N2 interface definition failure message or the update failure message, the information indicating the supported network slice to the PLMN served by the main network device. In this way, in a definition process, the first base station can also obtain the indication information of the supported network slice for the PLMN served by the main network device, thereby reducing the interaction for obtaining the network slice. supported, and increasing the speed at which the network slice indication information is obtained. For another example, the first message sent by the first base station to the main network device is also a request to define the N2 interface or a configuration update message from the base station. The first base station receives an N2 interface definition response message (N2 interface setup response) or a base station configuration acknowledgment message (for example, gNB configuration update ACK) from the main network device. The master network device can send, using the N2 interface definition reply message or a main network device configuration confirmation confirmation message, the supported network slice indication information for PLMN served by the network device main. In this way, the first base station can obtain the indication of the supported network slice indication from the PLMN served by the main network device, thereby improving the convenience of obtaining the network slice indication information.

[0219] Optionally, there is a communications interface between the first base station and the main network device. For example, the first message is a fetch request. The main network device can send, using a reply message, the information indicating the supported network slice of the PLMN served by the main network device. For another example, the first message sent by the first

Petition 870190095647, of 09/24/2019, p. 141/212

61/94 base station to the main network device can be a base station configuration update message (for example, gNB configuration update). The first base station receives a base station configuration update failure message (for example, gNB configuration update failure) from the main network device. The main network device can send, using the update failure message, the indication of the supported network slice of the PLMN served from the main network device. For another example, if the first message sent by the first base station to the primary network device is also a base station configuration update message, the first base station will receive an update message from the base station configuration update. base (for example, gNB configuration update ACK) from the primary network device. The main network device can send, using a confirmation message to update the configuration of the main network device, the indication information of the supported network slice of the PLMN served by the main network device. In this way, the first base station can obtain the indication of the supported network slice indication from the PLMN served by the main network device, thereby improving the convenience of obtaining the network slice indication information.

[0220] It should be understood that there is no chance or necessary sequence between step 501 and step 502. For example, step 502 can be independently implemented, provided that the main network device determines, before step 502, the information of indication of the supported network slice for the PLMN served by the main network device. For example, the main network device can proactively implement step 502 when determining the supported network slice of the PLMN served from the main network device is updated. In this case, the second message is an AMF configuration update message (for example, AMF configuration update), to notify the first base station of indication of an updated supported network slice indication to the PLMN served by the network device. main.

[0221] It should be noted that, in this embodiment of the present invention, a PLMN served by the main network device can also be

Petition 870190095647, of 09/24/2019, p. 142/212

62/94 is understood as a PLMN supported by the main network device, and this is not limited in this embodiment of the present invention.

[0222] In this embodiment of the present invention, the first base station can obtain, using the main network device, the indication information of the supported network slice for the PLMN served by the main network device, and return, at the granularity of PLMN, the network slice supported by the main network device, to improve the accuracy of selection, by the first base station, of the main network device for the terminal device session.

[0223] With reference to FIGURE 6, FIGURE 6 shows another method of communication according to one embodiment of the present invention. In this embodiment, an example where an access network device is a base station is used for the description. As shown in FIGURE 6, the method of communication refers to a terminal device, a source base station, a target base station and a main network device. FIGURE 6 corresponds to a communication method used when the main network device determines the failure to prepare for automatic switching. The source base station is a base station that currently establishes a communication connection with the terminal device. The target base station is a base station to which a session of the terminal device is requested to be switched automatically.

[0224] As shown in FIGURE 6, the communication method includes step 601 to step 606. For details, see the specific descriptions below.

[0225] 601. The source base station sends a first automatic change request to the main network device.

[0226] There is a communication interface, such as an N2 interface or an NG interface between the source base station and the main network device. Therefore, the source base station and the main network device can communicate. The first automatic change request is used to request the automatic change of the session from the terminal device from the source base station to the target base station. For example, the first automatic change request is automatic change required. The first automatic change request includes information about the base station

Petition 870190095647, of 09/24/2019, p. 143/212

63/94 target and an identifier of a session requested to be changed automatically. The primary network device can determine, by using information about the target base station, a base station / cell for which the terminal device session should be switched automatically. The primary network device can determine, by using the identifier of the requested session to be changed automatically, a session that will be changed automatically. There may be one or more requested sessions that will be switched automatically and different sessions may correspond to different network slices. The different network slices correspond to the different network slice indication information.

[0227] Optionally, the information about the target base station includes at least one among an identity of the base station of the target base station, an identity of the central unit of the target base station, an identity of the distributed unit of the base station target, a physical cell identifier of the target base station, or a global cell identity of the target base station.

[0228] Optionally, the first automatic change request additionally includes indication information of a network slice corresponding to the requested session to be changed automatically. Thus, the main network device can directly determine the network slice corresponding to the session that will be changed automatically, thereby saving the time used to search for the network slice corresponding to the session, reducing an automatic change delay and increasing a rate of change. automatic switching success. It can be understood that the first automatic change request may not include the indication information of the network slice corresponding to the requested session to be changed automatically. This is not limited in this embodiment of the present invention.

[0229] For example, the main network device is an AMF network element. If the AMF network element cannot store the network slice indication information corresponding to a session, the network slice indication information corresponding to each session needs to be carried forward in the first automatic change request.

[0230] Optionally, a first session includes a plurality of data streams. For example, the data flow is either a traffic flow or a flow

Petition 870190095647, of 09/24/2019, p. 144/212

64/94 QoS (QoS flow). The first automatic change request additionally includes a data flow identifier (for example, the data flow identifier includes a QoS flow ID) that needs to be established and that corresponds to the session and additionally includes QoS information ( for example, priority information) corresponding to each of the various data streams in the session. The main network device includes an AMF network element and an SMF network element on one side of the main network. The AMF network element first receives a first automatic change request message sent by the source base station and the AMF network element sends a second automatic change request message to the target base station. The second automatic change request message must include an identifier for a session data stream that will be changed automatically and data flow QoS information. However, the information is not stored in the AMF network element. Therefore, if the information is carried on the first automatic change request, the AMF network element does not need to obtain the information from the SMF network element, thereby saving search time, reducing an automatic change delay and improving efficiency of automatic switching.

[0231] Optionally, the first automatic change request additionally includes aggregate maximum bit rate (AMBR) information corresponding to the session, for example, signed AMBR information. The target base station can perform traffic control over the data flow based on this part of the information, but the information needs to be sent by the main network device to the target base station. In this case, the main network device includes the AMF network element and the SMF network element on the main network side. Because the AMF network element does not store this part of the information, the information is added to the first automatic change request, to reduce the time used to search the SMF network element for information by the AMF network element. This can save research time, reduce an automatic switching delay and improve the efficiency of automatic switching.

[0232] Optionally, the first automatic change request

Petition 870190095647, of 09/24/2019, p. 145/212

65/94 additionally includes the first indication information and the indication information indicates that the source base station does not determine or know a supported network slice from the target base station, so that the main network device obtains that the station source base does not know the information about the supported network slice of the target base station. Therefore, information about the supported network slice of the target base station can be added to a first automatic change response message. This reduces the interaction between the source base station and the target base station and improves the effectiveness of obtaining information about the network slice.

[0233] Optionally, the target base station can be a base station that has a communication interface with the source base station, or it can be a base station that has no communication interface with the source base station. Optionally, the first automatic change request may include the second indication information indicating that there is no communication interface between the source base station and the target base station. This helps the main network device to provide information about the supported network slice of the target base station.

[0234] Optionally, the source base station selects one from a plurality of base stations that have a communication interface with the source base station as the target base station. In addition, the target target base station supports the network slices corresponding to all or some requested sessions that will be changed automatically, so that an automatic change failure caused by the fact that the target base station does not support the slices of the network of all requested sessions that will be changed automatically is avoided, and a number of failures in the automatic change are reduced, to increase a success rate of automatic change.

[0235] Optionally, if the source base station receives a measurement report sent by the terminal device, the source base station can select the target base station based on the measurement report, and perform step 601 to send the request for automatic switching to the target base station. The measurement report includes a measurement report of at least one between a cell and a base station. Optionally, if

Petition 870190095647, of 09/24/2019, p. 146/212

66/94 the measurement report includes a cell measurement report value, the included cell can be a cell from the source base station or a cell from another base station. If the measurement report includes a measurement report value from the base station, the included base station can be the source base station or another base station. Optionally, a number of cells and a number of base stations included in the measurement report are not limited in this embodiment of the present invention.

[0236] 602. The main network device determines the indication information of a network slice corresponding to a requested session to be changed automatically.

[0237] Step 602 is an optional step. If the first automatic change request does not include the information for indicating the network slice corresponding to the session, the primary network device can search, based on an identifier of the session requested to be automatically changed, for a stored match between a session identifier and network slice indication information for the network slice indication information corresponding to the requested session to be changed automatically. Correspondence stored on the primary network device may include an identifier or identifiers for one or more sessions of the terminal device and indication information for a corresponding network slice.

[0238] If the first automatic change request includes the network slice indication information corresponding to the requested session identifier to be automatically changed, the main network device can directly determine the network slice indication information corresponding to the requested session to be changed automatically. The time used by the primary network device to search for the indication of the network slice corresponding to the requested session to be changed automatically can be reduced.

[0239] In addition, the first automatic change request may include information about the target base station and the primary network device determines, based on information about the target base station, information about the supported network slice of the target base station. Information about the network slice includes information about the slice indication

Petition 870190095647, of 09/24/2019, p. 147/212

67/94 network supported. In a specific example, the session requested to be changed automatically is defined as an E1 session. When there is a communication interface between the target base station and the main network device, if the main network device obtains information about a first supported network slice from the target base station, the main network device can directly determine the information indication of the first supported network slice of the target base station. If the primary network device does not obtain information about the first supported network slice from the target base station, the primary network device can obtain information from the target base station, indicating the information for the first supported network slice from the target base station. target base station. In addition, the main network device can determine whether the indication information for the first supported network slice of the target base station includes the indication information for a second network slice corresponding to the E1 session. If the indication information for the first supported network slice of the target base station includes the indication information for the second network slice corresponding to the E1 session, this indicates that the target base station supports a network slice corresponding to the E1 session. If the indication information for the first supported network slice of the target base station does not include the indication information for the second network slice corresponding to the E1 session, this indicates that the target base station does not support the network slice corresponding to the E1 session .

[0240] Then, if the indication information for the first supported network slice of the target base station does not include indication information for the second network slices corresponding to all requested sessions that will be changed automatically, the main network device can determine that the target base station does not support the network slice corresponding to the requested session to be changed automatically. The main network device can perform step 605 in FIGURE 6 and the main network device sends the first automatic change response message to the source base station. In this case, the first automatic change response message can be a first automatic change failure message. The first automatic change failure message includes rejection indication information used to indicate that the target base station does not support network slices

Petition 870190095647, of 09/24/2019, p. 148/212

68/94 corresponding to all requested sessions that will be changed automatically. Optionally, the rejection indication information can be indicated by using an IE, an indicator, a cause or the like, and this is not limited in this embodiment of the present invention.

[0241] Alternatively, if the target base station supports the network slices corresponding to all or some requested sessions that will be changed automatically, the main network device performs step 603 in FIGURE 6, and the main network device sends a second automatic switch request to the target base station.

[0242] 603. The main network device sends a second automatic change request to the target base station.

[0243] For example, the second automatic change request is an automatic change request. The second automatic change request includes the session identifier corresponding to the requested session to be changed automatically and the indication of the network slice corresponding to the requested session to be changed automatically.

[0244] Optionally, the second automatic change request includes session identifiers for all sessions requested by the source base station that will be changed automatically and indication information for a network slice corresponding to each session.

[0245] Optionally, after the main network device performs step 602, the main network device can classify the sessions requested by the source base station which will be changed automatically in a first session and a second session. A network slice corresponding to the first session is supported by the target base station. A network slice corresponding to the second session is not supported by the target base station. In addition, the second automatic change request may include only an identifier for the first session and information for indicating the network slice corresponding to the first session. Or, the second automatic change request includes the identifier of the first session, an identifier of the second session, the indication information for the network slice corresponding to the first session, and the indication information for the network slice corresponding to the second session. This is not limited in the embodiments of the present invention.

Petition 870190095647, of 09/24/2019, p. 149/212

69/94 [0246] Correspondingly, the target base station receives the second automatic change request.

[0247] 604. The target base station sends a second automatic change failure message to the main network device.

[0248] The target base station receives the second automatic change request from the main network device and determines whether the target base station can serve the session included in the second automatic change request. If the target base station cannot serve any session, the second auto-change response message sent to the main network device at step 604 in FIGURE 6 can be the second auto-change failure message, for example, a request for automatic shift failure or automatic shift failure, the second automatic shift failure message can also be an automatic shift preparation failure message (automatic shift preparation failure). The second automatic change failure message includes cause information for a rejected session.

[0249] In addition, the cause information for the rejected session can be: the target base station does not support a network slice corresponding to the rejected session or a resource is not available for a network slice that will be supported by the target base station and corresponding to the rejected session.

[0250] For the specific implementation of the second automatic change failure message in this modality of the present invention, refer to the specific descriptions of the automatic change failure message in step 403 in the modality shown in FIGURE 4. Details are not described again in this report .

[0251] Correspondingly, the main network device receives the second automatic change failure message sent by the target base station.

[0252] 605. The main network device sends a first automatic change response message to the source base station.

[0253] The main network device sends the first automatic change response message to the source base station. In this

Petition 870190095647, of 09/24/2019, p. 150/212

70/94 mode, the first automatic change response message is the first automatic change failure message. For example, the first automatic change failure message is an automatic change preparation failure message (automatic change preparation failure). The first automatic change response message includes the rejection indication information. Reject indication information is used to indicate cause information corresponding to a session, which is rejected by the target base station, due to a network slice, from the requested session to be changed automatically.

[0254] Optionally, the first automatic change failure message includes a rejected session identifier and cause information corresponding to the rejected session identifier.

[0255] Optionally, if the main network device sends, to the target base station, identifiers of all sessions requested by the source base station that will be changed automatically, the identifier of the rejected session and the cause information corresponding to the rejected session that are included in the first automatic change failure message are the same as the rejected session identifier and the cause information corresponding to the rejected session that are included in the second automatic change failure message.

[0256] Optionally, if the main network device sends, to the target base station, the first session identifier in all sessions requested by the source base station that will be changed automatically, and the first session is a session that is in the requested sessions that will be changed automatically and whose corresponding network slice is supported by the target base station, the first automatic change failure message includes an identifier from a rejected first session, cause information corresponding to the rejected first session, an identifier from a rejected session second session rejected and cause information corresponding to the second session rejected. The first rejected session is a session that is rejected and that is included in the second automatic change failure message and the second rejected session is a session that in the requested sessions that will be automatically changed and whose corresponding network slice is not supported by the station. target base. The second rejected session identifier and the

Petition 870190095647, of 09/24/2019, p. 151/212

71/94 cause information corresponding to the second rejected session is determined by the main network device.

[0257] Optionally, the primary network device adds, to the first automatic change response message, information about the supported network slice of the target base station, for example, if the first automatic change request includes the first indication indicating that the source base station does not know the supported network slice of the target base station, or the primary network device determines, based on an indication that is carried on the first automatic change request and that there is no interface of communication between the source base station and the target base station, that the source base station does not know the supported network slice of the target base station. This reduces the interaction between the source base station and the target base station and improves the effectiveness of obtaining information about the network slice.

[0258] 606. Optionally, the source base station sends an RRC connection release message to the terminal device.

[0259] For step 606, see the detailed descriptions of step 404 in the mode shown in FIGURE 4. The details are not described again in this report.

[0260] In this embodiment of the present invention, after the source base station sends the automatic change request to the main network device, the source base station can obtain the cause information for the session, which is rejected by the base station target, due to a network slice, to help provide information for another session that needs to be requested that will automatically be switched to the target base station. When a session corresponding to the same network slice needs to be switched automatically from the source base station, the source base station can directly determine whether the session can be automatically switched to the target base station, thereby increasing an exchange rate. automatic switching success.

[0261] With reference to FIGURE 7, FIGURE 7 shows another method of communication, according to an embodiment of the present invention. In this embodiment, an example in which an access network device is a base station is used for description. As shown in FIGURE 7, the

Petition 870190095647, of 09/24/2019, p. 152/212

72/94 communication method refers to a terminal device, a source base station, a target base station and a main network device. FIGURE 7 corresponds to a communication method used when the main network device determines that the automatic switch was successful. The source base station is a base station that currently establishes a communication connection to the terminal device and the target base station is a base station to which a session of the terminal device is requested to be switched automatically.

[0262] As shown in FIGURE 7, the communication method includes step 701 to step 707. For details, see the specific descriptions below.

[0263] 701. The source base station sends a first automatic change request to the main network device.

[0264] 702. The main network device determines the indication information of a network slice corresponding to a requested session to be changed automatically.

[0265] 703. The main network device sends a second automatic switch request to the target base station.

[0266] For step 701 to step 703, refer to the corresponding detailed descriptions of steps 601 to 603 in the mode shown in FIGURE 6. Details are not described again in this report.

[0267] 704. The target base station sends a second automatic change request acknowledgment message to the primary network device.

[0268] The second automatic change request acknowledgment message includes an accepted session identifier. For example, the second automatic change request acknowledgment message is automatic change request acknowledgment.

[0269] Optionally, the first automatic change reply message can additionally include an identifier for a rejected session and cause information corresponding to the rejected session.

[0270] Optionally, the second automatic change request acknowledgment message additionally includes retransmission indication information corresponding to the rejected session. The informations

Petition 870190095647, of 09/24/2019, p. 153/212

73/94 retransmission indication is used to indicate whether the terminal device is allowed to route, to a supported network slice of the target base station, a rejected session data stream. For example, the rejected session is a B1 session and session B1 corresponds to a network slice 1. The cause information for the rejected session B1 can be as follows: the target base station does not support the network slice 1 corresponding to the session B1 or the target base station supports network slice 1, but a feature is not available for network slice 1. Notwithstanding a reason to reject session B1, if the target base station supports network slice 2 and if a data stream from session B1 is routed to network slice 2, data transmission can also be implemented. In this case, the target base station determines that the retransmission indication information corresponding to session B1 is: the terminal device is allowed to route the data stream from session B1 to the network slice 2 supported by the target base station. In addition, if a network slice to which the data stream of the B1 session can be routed does not exist at the target base station, the target base station determines that the relay indication information corresponding to the B1 session is: the device terminal is not allowed to route the data stream from session B1 to the supported network slice of the target base station.

[0271] Optionally, the automatic change request acknowledgment message additionally includes an identifier of a rejected carrier or an identifier of a rejected data stream of the requested session to be changed automatically. For details, refer to the detailed descriptions of step 303 in the mode shown in FIGURE 3. The details are not described again in this report.

[0272] The second automatic change request acknowledgment message in this embodiment of the present invention can refer to the automatic change request acknowledgment message in the mode shown in FIGURE 3. The second automatic change request acknowledgment message includes the identifier of the accepted session, the rejected session identifier and the cause information corresponding to the rejected session. The second automatic change request acknowledgment message is sent to the main network device [0273] 705. The main network device sends a first

Petition 870190095647, of 09/24/2019, p. 154/212

74/94 automatic change request acknowledgment message to the source base station.

[0274] The main network device sends a first automatic change response message to the source base station. In this mode, the first automatic change response message is the first automatic change request acknowledgment message. For example, the first automatic change request acknowledgment message is an automatic change command (Handover command). The first automatic change request acknowledgment message includes the accepted session identifier.

[0275] Optionally, the first automatic change reply message can additionally include the rejected session identifier and the cause information corresponding to the rejected session.

[0276] Optionally, if the main network device sends, to the target base station, identifiers for all sessions requested by the source base station that will be changed automatically, an identifier for a rejected session and cause information corresponding to the rejected session that are included in the first automatic change request acknowledgment message are the same as a rejected session identifier and cause information corresponding to the rejected session that are included in the second automatic change request acknowledgment message.

[0277] Optionally, if the main network device sends, to the target base station, an identifier of a first session in all sessions requested by the source base station that will be changed automatically and the first session is a session that is in the requested sessions that will be changed automatically and whose corresponding network slice is supported by the target base station, the first automatic change request acknowledgment message includes an identifier from a rejected first session, cause information corresponding to the rejected first session, an identifier second rejected session and cause information corresponding to the second rejected session. The first rejected session is a session that is rejected and that is included in the second automatic change request acknowledgment message and the

Petition 870190095647, of 09/24/2019, p. 155/212

75/94 second session rejected is a session that in the requested sessions that will be changed automatically and whose corresponding network slice is not supported by the target base station. The identifier of the second rejected session and the cause information corresponding to the second rejected session are determined by the main network device.

[0278] Optionally, the main network device adds information about the supported network slice of the target base station to the first auto-change reply message. For example, the first automatic change request includes the first indication information indicating that the source base station does not know the supported network slice of the target base station or the main network device determines, based on an indication that it is carried in the first automatic change request and that indicates that there is no communication interface between the source base station and the target base station, that the source base station does not know the supported network slice of the target base station. This reduces the interaction between the source base station and the target base station and improves the effectiveness of obtaining the network slice indication information.

[0279] 706. The source base station sends an automatic change command to the terminal device.

[0280] 707. The terminal device sends an automatic change acknowledgment message to the target base station.

[0281] For step 706 and step 707, see the detailed descriptions of step 304 and step 305 in the mode shown in FIGURE 3. The details are not described again in this report.

[0282] In this embodiment of the present invention, after the source base station sends the automatic change request to the main network device, the source base station can obtain the cause information for the session, which is rejected by the base station target, due to a network slice, to help provide information for another session that needs to be requested to be automatically switched to the target base station. When a session corresponding to the same network slice needs to be switched automatically from the source base station, the source base station can directly determine whether the session can be automatically switched to the target base station, thereby increasing an exchange rate. success of

Petition 870190095647, of 09/24/2019, p. 156/212

76/94 automatic change.

[0283] With reference to FIGURE 8, FIGURE 8 is a schematic structural diagram of a base station, according to an embodiment of this application. The base station can be a source base station and is configured to implement the mode in FIGURE 3 or FIGURE 4. As shown in FIGURE 8, the source base station includes:

a transmission unit 801 configured to send an automatic change request to a target base station, where the automatic change request is used to request the automatic change of a session from a terminal device from the source base station to the station base target and the automatic change request includes an identifier of a session requested to be changed automatically and indication information for a network slice corresponding to the session; and a receiving unit 802 configured to receive an automatic change response message from the target base station, where the automatic change response message includes rejection indication information and rejection indication information is used to indicate information of cause corresponding to a session, which is rejected by the target base station, due to a network slice, from the session requested to be changed automatically.

[0284] Optionally, the session requested to be changed automatically includes a first session or the session requested to be changed automatically includes the first session and a second session.

[0285] A network slice corresponding to the first session is supported by the target base station and a network slice corresponding to the second session is not supported by the target base station.

[0286] Optionally, the cause information is as follows: the target base station does not support a network slice corresponding to the rejected session or a resource is not available for a network slice that will be supported by the target base station and corresponding to the session rejected.

[0287] Optionally, if the automatic change response message is an automatic change request acknowledgment message, the automatic change response message additionally includes retransmission indication information corresponding to the

Petition 870190095647, of 09/24/2019, p. 157/212

77/94 session that is rejected by the target base station and the relay indication information corresponding to the session is used to indicate whether the terminal device is allowed to route, to a supported network slice of the target base station, a stream of rejected session data.

[0288] Optionally, the source base station sends an automatic change command to the terminal device, if the automatic change response message is an automatic change request acknowledgment message, where the automatic change command includes the information of retransmission indication corresponding to the session that is rejected by the target base station.

[0289] Optionally, if the automatic change response message is an automatic change request acknowledgment message, the automatic change request acknowledgment message additionally includes a rejected carrier identifier or a rejected data stream identifier. of the requested session to be changed automatically.

[0290] Optionally, the 801 transmission unit is additionally configured to send a radio resource control RRC connection release message to the terminal device, if the automatic change response message is an automatic change failure message.

[0291] Optionally, the RRC connection release message includes indication information for a neighboring cell of a source cell, indication information for a network slice supported by a TA / RA to which the neighboring cell of the source cell belongs, or information about a network slice supported by a base station neighboring the source base station.

[0292] It can be understood that, for specific implementations and corresponding beneficial effects of function blocks included in the base station in FIGURE 8, refer to the specific descriptions of the preceding modality in FIGURE 3 or FIGURE 4. Details are not described again in this report .

[0293] In this patent application, the transmitting unit can be a transmitter and the receiving unit can be a receiver.

[0294] With reference to FIGURE 9, FIGURE 9 is a diagram

Petition 870190095647, of 09/24/2019, p. 158/212

78/94 schematic structural of a base station, according to one embodiment of this application. The base station can be a target base station and is configured to implement the mode in FIGURE 3 or FIGURE 4. As shown in FIGURE 9, the target base station includes:

a receiving unit 901 configured to receive an automatic change request from a source base station, where the automatic change request is used to request the automatic change of a session from a terminal device from the source base station to the target base station and the automatic change request includes an identifier of a requested session to be changed automatically and indication information for a network slice corresponding to the session; and a transmission unit 902 configured to send an auto-change response message to the source base station, where the auto-change response message includes rejection indication information and rejection indication information is used to indicate rejection information. cause corresponding to a session, which is rejected by the target base station, due to a network slice, from the session requested to be changed automatically.

[0295] Optionally, the session requested to be changed automatically includes a first session or the session requested to be changed automatically includes the first session and a second session.

[0296] A network slice corresponding to the first session is supported by the target base station and a network slice corresponding to the second session is not supported by the target base station.

[0297] Optionally, the cause information is as follows: the target base station does not support a network slice corresponding to the rejected session or a resource is not available for a network slice that will be supported by the target base station and corresponding to the session rejected.

[0298] Optionally, the automatic change reply message additionally includes retransmission indication information corresponding to the session that is rejected by the target base station and the relay indication information corresponding to the session is used to indicate whether the terminal device is allowed to route, to a network slice supported by the target base station, a data stream from the

Petition 870190095647, of 09/24/2019, p. 159/212

79/94 session rejected.

[0299] Optionally, if the automatic change response message is an automatic change request acknowledgment message, the automatic change request acknowledgment message additionally includes a rejected carrier identifier or a rejected data stream identifier. of the requested session to be changed automatically.

[0300] Optionally, the receiving unit 901 is additionally configured to receive an automatic change acknowledgment message from the terminal device.

[0301] Transmission unit 902 is additionally configured to send a path switching request to a primary network device, where the path switching request includes a session identifier that is accepted by the target base station and an identifier of a session that is rejected by the target base station.

[0302] Receiving unit 901 is additionally configured to receive a path switch request response message from the primary network device, where the path switch request response message includes a session identifier for the which the path switch was successfully completed.

[0303] Optionally, the path switching request additionally includes information of indication of the network slice corresponding to the session that is rejected by the target base station.

[0304] Optionally, the path switching request additionally includes cause information corresponding to the session that is rejected by the target base station.

[0305] It can be understood that, for specific implementations and corresponding beneficial effects of function blocks included in the base station in FIGURE 9, refer to the specific descriptions of the preceding modality in FIGURE 3 or FIGURE 4. Details are not described again in this report .

[0306] With reference to FIGURE 10, FIGURE 10 is a schematic structural diagram of a main network device, according to an embodiment of this application. The primary network device is configured to

Petition 870190095647, of 09/24/2019, p. 160/212

80/94 implement the modality in FIGURE 4. As shown in FIGURE 10, the main network device includes:

a receiving unit 1001 configured to receive a trajectory switch request from a target base station, where the trajectory switch request includes a session identifier that is accepted by the target base station and a session identifier which is rejected by the target base station;

a processing unit 1002 configured to perform path switching in the accepted session and to deactivate or release the rejected session; and a transmission unit 1003 configured to send a path switch request response message to the target base station, where the path switch request response message includes an identifier of a session for which path switching is taking place. has been successfully completed.

[0307] Optionally, the path switching request additionally includes information for indicating a network slice corresponding to the session that is rejected by the target base station.

[0308] Optionally, the path switching request includes cause information corresponding to the session that is rejected by the target base station.

[0309] Optionally, the cause information is as follows: the target base station does not support the network slice corresponding to the rejected session or a resource is not available for a network slice that will be supported by the target base station and corresponding to the session rejected.

[0310] It can be understood that, for specific implementations and corresponding beneficial effects of function blocks included in the main network device in FIGURE 10, refer to the specific descriptions of the preceding modality in FIGURE 4. Details are not described again in this report.

[0311] In this patent application, the processing unit can be implemented in a form of a processor.

[0312] With reference to FIGURE 11, FIGURE 11 is a schematic structural diagram of a base station, according to a modality

Petition 870190095647, of 09/24/2019, p. 161/212

81/94 of this order. The base station can be a first base station and is configured to implement the modality in FIGURE 5. As shown in FIGURE 11, the base station includes:

a transmission unit 1101 configured to send a first message to a primary network device, where the first message is used to obtain information about a supported network slice from the primary network device to a PLMN; and a receiving unit 1102 configured to receive a second message from the main network device, where the second message includes information about a supported network slice of a PLMN served by the main network device.

[0313] It can be understood that, for specific implementations and corresponding beneficial effects of function blocks included in the base station in FIGURE 11, refer to the specific descriptions of the preceding modality in FIGURE 5. Details are not described again in this report.

[0314] With reference to FIGURE 12, FIGURE 12 is a schematic structural diagram of a main network device, according to an embodiment of this application. The main network device is configured to implement the mode in FIGURE 5. As shown in FIGURE 12, the main network device includes:

a receiving unit 1201 configured to receive a first message from a first base station, where the first message is used to obtain information about a supported network slice from the primary network device to a PLMN; and a transmission unit 1202 configured to send a second message to the first base station, where the second message includes information about a supported network slice of a PLMN served by the main network device.

[0315] It can be understood that, for specific implementations and corresponding beneficial effects of function blocks included in the main network device in FIGURE 12, refer to the specific descriptions of the preceding modality in FIGURE 5. Details are not described again in this report.

Petition 870190095647, of 09/24/2019, p. 162/212

82/94 [0316] With reference to FIGURE 13, FIGURE 13 is a schematic structural diagram of a base station, according to an embodiment of this application. The base station can be a source base station and is configured to implement the mode in FIGURE 6 or FIGURE 7. As shown in FIGURE 13, the source base station includes:

a transmission unit 1301 configured to send a first automatic change request to a primary network device, where the first automatic change request is used to request the automatic change of a session from a terminal device from the source base station to a target base station and the first automatic change request includes information about the target base station and an identifier of a session requested to be changed automatically; and a receiving unit 1302 configured to receive a first automatic change response message from the primary network device, where the first automatic change response message includes rejection indication information and rejection indication information is used to indicate cause information corresponding to a session, which is rejected by the target base station, due to a network slice, from the session requested to be changed automatically.

[0317] Optionally, the cause information is as follows: the target base station does not support a network slice corresponding to the rejected session or a resource is not available for a network slice that will be supported by the target base station and corresponding to the session rejected.

[0318] Optionally, if the first automatic change response message is a first automatic change request acknowledgment message, the first automatic change response message will additionally include retransmission indication information corresponding to the session that is rejected by the transmission station. target base and retransmission indication information corresponding to the session is used to indicate whether the terminal device is allowed to route a rejected session data stream to a supported network slice of the target base station.

[0319] Optionally, the 1301 transmission unit is configured

Petition 870190095647, of 09/24/2019, p. 163/212

83/94 additionally to send an automatic change command to the terminal device if the first automatic change response message is the first automatic change request acknowledgment message, where the automatic change command includes the corresponding retransmission indication information to the session that is rejected by the target base station.

[0320] Optionally, if the first automatic change response message is the first automatic change request acknowledgment message, the first automatic change request acknowledgment message will additionally include a rejected carrier identifier or a flow identifier of rejected data from the requested session to be changed automatically.

[0321] Optionally, transmission unit 1301 is additionally configured to send an RRC connection release message to the terminal device if the first automatic change response message is a first automatic change failure message.

[0322] Optionally, the RRC connection release message includes indication information for a network slice supported by a cell neighboring the source base station, indication information for a network slice supported by a TA / RA which the cell neighbor of the source base station belongs to or information about a network slice supported by a base station neighboring the source base station.

[0323] Optionally, if the first automatic change response message is the first automatic change request acknowledgment message, the first automatic change request acknowledgment message will additionally include information about the supported network slice of the target base station .

[0324] Optionally, the first automatic change request additionally includes information for indicating a network slice corresponding to the requested session to be changed automatically.

[0325] Optionally, the first automatic change request additionally includes an identifier for a session data stream that is requested to be changed automatically and needs to be established and corresponding QoS information for the data stream.

Petition 870190095647, of 09/24/2019, p. 164/212

84/94 [0326] Optionally, the first automatic change request additionally includes session aggregated maximum bit rate AMBR information.

[0327] It can be understood that, for specific implementations and corresponding beneficial effects of function blocks included in the base station in FIGURE 13, refer to the specific descriptions of the preceding modality in FIGURE 6 or FIGURE 7. Details are not described again in this report .

[0328] With reference to FIGURE 14, FIGURE 14 is a schematic structural diagram of a base station, according to an embodiment of this application. The base station can be a target base station and is configured to implement the mode in FIGURE 6 or FIGURE 7. As shown in FIGURE 14, the target base station includes:

a receiving unit 1401 configured to receive a second automatic change request from a primary network device, where the second automatic change request includes a session identifier and indication information for a corresponding network slice; and a transmission unit 1402 configured to send a second auto-change response message to the source base station, where the second auto-change response message includes rejection indication information and rejection indication information is used to indicate cause information corresponding to a session, which is rejected by the target base station, due to a network slice, from the session requested to be changed automatically.

[0329] Optionally, the session included in the second automatic change request is a first session or the session included in the second automatic change request is the first session and a second session.

[0330] A network slice corresponding to the first session is supported by the target base station and a network slice corresponding to the second session is not supported by the target base station.

[0331] Optionally, the cause information is as follows: the target base station does not support a network slice corresponding to the rejected session or a resource is not available for a network slice that will be

Petition 870190095647, of 09/24/2019, p. 165/212

85/94 supported by the target base station and corresponding to the rejected session.

[0332] Optionally, if the second automatic change response message is a second automatic change request acknowledgment message, the second automatic change response message additionally includes retransmission indication information corresponding to the session that is rejected by the transmission station. target base and retransmission indication information corresponding to the session is used to indicate whether the terminal device is allowed to route a rejected session data stream to a supported network slice of the target base station.

[0333] Optionally, if the second automatic change response message is the second automatic change request acknowledgment message, the second automatic change request acknowledgment message additionally includes a rejected carrier identifier or a flow identifier of rejected data from the session included in the second automatic change request.

[0334] It can be understood that, for specific implementations and corresponding beneficial effects of function blocks included in the base station in FIGURE 14, refer to the specific descriptions of the preceding modality in FIGURE 6 or FIGURE 7. Details are not described again in this report .

[0335] With reference to FIGURE 15, FIGURE 15 is a schematic structural diagram of a main network device, according to an embodiment of this application. The main network device is configured to implement the mode in FIGURE 6 or FIGURE 7. As shown in FIGURE 15, the main network device includes:

a receiving unit 1501 configured to receive a first automatic change request from a source base station, where the first automatic change request is used to request the automatic change of a session from a terminal device from the base station source for a target base station and the first automatic change request includes information about the target base station and an identifier for a session requested to be changed automatically; and a transmission unit 1502 configured to send a

Petition 870190095647, of 09/24/2019, p. 166/212

86/94 first auto-change reply message to the source base station, where the first auto-change reply message includes rejection indication information and rejection indication information is used to indicate cause information corresponding to a session , which is rejected by the target base station, due to a network slice, from the requested session to be changed automatically.

[0336] Optionally, the cause information is as follows: the target base station does not support a network slice corresponding to the rejected session or a resource is not available for a network slice that will be supported by the target base station and corresponding to the session rejected.

[0337] Optionally, if the first automatic change response message is a first automatic change request acknowledgment message, the first automatic change response message additionally includes retransmission indication information corresponding to the session that is rejected by the transmission station. target base and retransmission indication information corresponding to the session is used to indicate whether the terminal device is allowed to route a rejected session data stream to a supported network slice of the target base station.

[0338] Optionally, if the first automatic change response message is the first automatic change request acknowledgment message, the first automatic change request acknowledgment message will additionally include a rejected carrier identifier or a flow identifier of rejected data from the requested session to be changed automatically.

[0339] Optionally, if the first automatic change response message is the first automatic change request acknowledgment message, the first automatic change request acknowledgment message will additionally include information about the supported network slice of the target base station or information indicating a supported network slice of a TA / RA to which a target base station cell belongs.

[0340] Optionally, the first automatic change request additionally includes indication information for a network slice

Petition 870190095647, of 09/24/2019, p. 167/212

87/94 corresponding to the requested session to be changed automatically.

[0341] Optionally, the first automatic change request additionally includes an identifier for a session data stream that is requested to be changed automatically and needs to be established and corresponding QoS information for the data stream.

[0342] Optionally, the first automatic change request additionally includes AMBR information of the aggregated maximum bit rate corresponding to the session.

[0343] Optionally, the transmission unit 1502 is additionally configured to send a second automatic change request to the target base station, where the second automatic change request includes a session identifier and network slice indication information corresponding to the session.

[0344] Receiving unit 1501 is additionally configured to receive a second automatic change response message from the target base station, where the second automatic change response message includes the rejection indication information.

[0345] Optionally, the session included in the second automatic change request is a first session or the session included in the second automatic change request is the first session and a second session.

[0346] A network slice corresponding to the first session is supported by the target base station and a network slice corresponding to the second session is not supported by the target base station.

[0347] Optionally, if the second automatic change response message is a second automatic change request acknowledgment message, the second automatic change response message will additionally include retransmission indication information corresponding to the session that is rejected by the transmission station. target base and retransmission indication information corresponding to the session is used to indicate whether the terminal device is allowed to route a rejected session data stream to a supported network slice of the target base station.

[0348] Optionally, if the second auto-change reply message is the second request acknowledgment message

Petition 870190095647, of 09/24/2019, p. 168/212

88/94 of automatic change, the second automatic change request acknowledgment message will additionally include an identifier of a rejected holder or an identifier of a rejected data stream of the session included in the second automatic change request.

[0349] It can be understood that, for specific implementations and corresponding beneficial effects of function blocks included in the main network device in FIGURE 15, refer to the specific descriptions of the preceding modality in FIGURE 6 or FIGURE 7. Details are not described again in this report.

[0350] In this patent application, each unit of determination can be implemented in a form of a processor.

[0351] With reference to FIGURE 16, FIGURE 16 is a schematic structural diagram of a terminal device, according to an embodiment of this application. The terminal device can be a terminal device and is configured to implement the mode in FIGURE 4 or FIGURE 6. As shown in FIGURE 16, the terminal device includes:

a receiving unit 1601 configured to receive a radio resource control RRC connection release message from a source base station; and a processing unit 1602 configured to release an RRC connection, where the RRC connection release message includes indication information of a supported network slice from a neighboring cell of a source cell, indication information of a supported network slice from a TA / RA to which the neighboring cell of the source cell belongs or information about a supported network slice from a base station neighboring the source base station.

[0352] It can be understood that, for specific implementations and corresponding beneficial effects of function blocks included in the terminal device in FIGURE 16, refer to the specific descriptions of the preceding modality in FIGURE 4 or FIGURE 6. Details are not described again in this report.

[0353] The base station in the embodiment shown in FIGURE 8, FIGURE 9, FIGURE 11, FIGURE 13 or FIGURE 14 can be implemented by a base station 1700 shown in FIGURE 17. As shown in

Petition 870190095647, of 09/24/2019, p. 169/212

89/94

FIGURE 17, FIGURE 17 is a schematic structural diagram of another base station, according to an embodiment of the present invention. The base station 1700 shown in FIGURE 17 includes a processor 1701 and a transceiver 1702. Transceiver 1702 is configured to support transmission of information between the base station 1700 and the main network device or other base station in the foregoing embodiments. Processor 1701 is communicatively connected to transceiver 1702, for example, connected to transceiver 1702 using a bus. Base station 1700 may additionally include memory 1703. Memory 1703 is configured to store data and program codes that are executed by base station 1700 and processor 1701 is configured to execute application program code stored in memory 1703 to implement actions performed by the base station provided in any of the modalities shown in FIGURE 3 to FIGURE 7.

[0354] It should be noted that, in the real application, the base station may include one or more processors, and a structure of the 1700 base station is not a limitation in this modality of this request.

[0355] The 1701 processor can be a central processing unit (CPU), a network processor (network processor, NP), a hardware chip, or any combination thereof. The hardware chip may be an application-specific integrated circuit (ASIC), a programmable logic device (programmable logic device, PLD) or a combination thereof. The PLD can be a complex programmable logic device (CPLD), a field programmable gate array (FPGA), generic array logic (GAL), or any combination of the same.

[0356] Memory 1703 may include a volatile memory, for example, a random access memory, RAM. Alternatively, 1703 memory may include nonvolatile memory, for example, read-only memory, ROM, instant memory (flash memory), hard disk drive , HDD) or a solid-state drive (SSD). Alternatively, memory 1703 may include a combination of

Petition 870190095647, of 09/24/2019, p. 170/212

90/94 types of previous memories.

[0357] One embodiment of the present invention further provides a computer storage medium and the computer storage medium can be configured to store a computer software instruction used by the base station in the embodiment shown in FIGURE 8, FIGURE 9, FIGURE 11, FIGURE 13 or FIGURE 14. The computer software instruction includes a program that is assigned to the base station to perform the preceding mode. Storage media includes, but is not limited to, flash memory, a hard disk drive, and a solid state drive.

[0358] One embodiment of the present invention additionally provides a computer program product. When executed by a computing device, the computer product can implement the communication method designated for the base station in the embodiment in FIGURE 8, FIGURE 9, FIGURE 11, FIGURE 13 or FIGURE 14.

[0359] The main network device shown in FIGURE 10, FIGURE 12, or FIGURE 15 can be implemented by a main network device 1800 shown in FIGURE 18. As shown in FIGURE 18, FIGURE 18 is a schematic structural diagram of another main network device, according to an embodiment of the present invention. The main network device 1800 shown in FIGURE 18 includes a processor 1801 and a transceiver 1802. Transceiver 1802 is configured to support transmission of information between the main network device 1800 and the base station in the foregoing embodiments. Processor 1801 is communicatively connected to transceiver 1802, for example, connected to transceiver 1802 using a bus. Main network device 1800 can additionally include memory 1803. Memory 1803 is configured to store data and program codes that are run by main network device 1800 and processor 1801 is configured to run application program code stored in memory 1803 to implement the actions performed by the main network device provided in any of the modalities shown in FIGURE 4 to FIGURE 7.

[0360] It should be noted that, in the actual application, the main network device may include one or more processors and a

Petition 870190095647, of 09/24/2019, p. 171/212

91/94 main network device 1800 does not constitute a limitation in this embodiment of this request.

[0361] The 1801 processor can be a CPU, an NP, a hardware chip or any combination thereof. The hardware chip can be an ASIC, a PLD or a combination thereof. The PLD can be a CPLD, an FPGA, GAL, or any combination thereof.

[0362] Memory 1803 may include volatile memory, such as RAM. Alternatively, memory 1803 may include non-volatile memory, such as a ROM, flash memory, a hard disk drive or a solid state drive. Alternatively, memory 1803 may include a combination of the preceding memory types.

[0363] One embodiment of the present invention additionally provides a computer storage medium and the computer storage medium can be configured to store a computer software instruction used by the main network device in the embodiment shown in FIGURE 10, FIGURE 12 or FIGURE 15. The computer software instruction includes a program that is assigned to the main network device to perform the preceding mode. Storage media includes, but is not limited to, flash memory, a hard disk drive, and a solid state drive.

[0364] One embodiment of the present invention additionally provides a computer program product. When run by a computing device, the computer product can implement the communication method designated for the main network device in the embodiment in FIGURE 10, FIGURE 12 or FIGURE 15.

[0365] The terminal device in the embodiment shown in FIGURE 16 can be implemented by a terminal device 1900 shown in FIGURE 19. As shown in FIGURE 19, FIGURE 19 is a schematic structural diagram of another terminal device, according to an embodiment of present invention. The terminal device 1900 shown in FIGURE 19 includes a processor 1901 and a transceiver 1902. Transceiver 1902 is configured to support transmission of information between terminal device 1900 and the base station in the foregoing embodiments. The 1901 processor is communicatively connected to the 1902 transceiver, for example, connected to the

Petition 870190095647, of 09/24/2019, p. 172/212

92/94 1902 transceiver for using a bus. Terminal device 1900 may additionally include memory 1903. Memory 1903 is configured to store data and program codes that are executed by terminal device 1900 and processor 1901 is configured to execute application program code stored in memory 1903 to implement actions performed by the terminal device provided in both the mode shown in FIGURE 4 and the mode shown in FIGURE 6.

[0366] It should be noted that, in the real application, the terminal device may include one or more processors and a structure of the terminal device 1900 does not constitute a limitation in this modality of this request.

[0367] The 1901 processor can be a CPU, an NP, a hardware chip or any combination thereof. The hardware chip can be an ASIC, a PLD or a combination thereof. The PLD can be a CPLD, an FPGA, GAL, or any combination thereof.

[0368] Memory 1903 may include volatile memory, such as RAM. Alternatively, memory 1903 may include non-volatile memory, such as a ROM, flash memory, a hard disk drive or a solid state drive. Alternatively, memory 1903 may include a combination of the preceding types of memories.

[0369] One embodiment of the present invention additionally provides a computer storage medium and the computer storage medium can be configured to store a computer software instruction used by the terminal device in the embodiment shown in FIGURE

16. The computer software instruction includes a program that is designed for the terminal device to perform the preceding mode. Storage media includes, but is not limited to, flash memory, a hard disk drive, and a solid state drive.

[0370] One embodiment of the present invention further provides a computer program product. When executed by a computing device, the computer product can perform the communication method designated for the terminal device in the embodiment in FIGURE

16.

[0371] In the specification, claims, and attached drawings of this application, the terms “first”, “second”, “third”, “fourth” and so on

Petition 870190095647, of 09/24/2019, p. 173/212

93/94 onwards intend to distinguish between different objects, but do not indicate a particular order. In addition, the term "including", "include" or any other variant thereof is intended to cover a non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the steps or units listed, but optionally additionally includes an unlisted step or unit or, optionally, it additionally includes another step or unit inherent in the process, method, product or device.

[0372] One skilled in the art can understand that the sequence numbers of the preceding processes do not mean sequences of execution in various modalities of this request. The sequences of execution of the processes must be determined, according to the functions and internal logic of the processes, and must not be interpreted as any limitation in the processes of implementation of the modalities of this request.

[0373] All or some of the preceding modalities can be implemented using software, hardware, firmware or any combination thereof. When software is used to implement the modalities, the modalities can be implemented completely or partially in a form of a computer program product. The computer program product includes one or more computer instructions. When the instructions of the computer program are loaded and executed on the computer, the procedure or functions, according to the modalities of the present invention, are all or partially generated. The computer can be a general purpose computer, a dedicated computer, a computer network or other programmable devices. Computer instructions can be stored on a computer-readable storage medium or they can be transmitted from a computer-readable storage medium to another computer-readable storage medium. For example, computer instructions can be transmitted from one website, computer, server or data center to another website, computer, server or data center in a wired manner (for example, a coaxial cable, an optical fiber or a digital subscriber line (DSL)) or wireless (for example, infrared, radio and microwave, or the like). Computer-readable storage media

Petition 870190095647, of 09/24/2019, p. 174/212

94/94 can be any usable media accessible by a computer, or a data storage device, such as a server or a data center, integrating one or more usable media. Usable media can be magnetic media (for example, a floppy disk, hard drive or magnetic tape), optical media (for example, DVD), semiconductor media (for example, Solid State Disk (SSD)), or the like.

[0374] A person skilled in the art can understand that all or some of the method methods in the modalities can be implemented by a computer program that instructs the relevant hardware. The program can be stored on a computer-readable storage medium. When the program is executed, the method processes in the modalities are carried out. The preceding storage media may include: a magnetic disk, an optical disk, a read-only memory (Read-Only Memory, ROM), or a random access memory (Random Access Memory, RAM).

[0375] What is disclosed above is merely exemplary modalities of the present invention and is certainly not intended to limit the scope of protection of the present invention. Therefore, equivalent variations made, according to the claims of the present invention, should be within the scope of the present invention.

Claims (80)

1. Communication method, comprising: send, through a source base station, an automatic change request to a target base station, where the automatic change request is used to request the automatic change of a session from a terminal device from the source base station to the station target base, and the automatic change request comprises an identifier of a session requested to be changed automatically and indication information for a network slice corresponding to the session; and receiving, by the source base station, an automatic change response message from the target base station, wherein the automatic change response message comprises rejection indication information, and rejection indication information is used to indicate information of cause corresponding to a session, which is rejected by the target base station due to a network slice, from the session requested to be changed automatically. A method according to claim 1, wherein the session requested to be changed automatically comprises a first session, or the session requested to be changed automatically comprises the first session and a second session; and a network slice corresponding to the first session is supported by the target base station, and a network slice corresponding to the second session is not supported by the target base station. 3. Method according to claim 1 or 2, in which the cause information is that: the target base station does not support a network slice corresponding to the rejected session, or a resource is not available for a network slice that is supported by the target base station and corresponding to the rejected session. Method according to any one of claims 1 to 3, wherein if the automatic change response message is an automatic change request acknowledgment message, the automatic change response message will additionally comprise retransmission indication information corresponding to the session that is rejected by Petition 870190095647, of 09/24/2019, p. 176/212 2/16 target base station, and the retransmission indication information corresponding to the session will be used to indicate whether the terminal device is allowed to route, for a supported network slice from the target base station, a rejected session data stream . A method according to claim 4, further comprising: send an automatic change command to the terminal device from the source base station if the automatic change response message is the automatic change request acknowledgment message, where the automatic change command comprises retransmission indication information corresponding to the session that is rejected by the target base station. 6. Method according to any one of claims 1 to 5, wherein if the automatic change response message is an automatic change request acknowledgment message, the automatic change request acknowledgment message will additionally comprise an a rejected carrier or an identifier of a rejected data stream from the requested session to be changed automatically. Method according to any one of claims 1 to 3, further comprising: send, through the source base station, an RRC radio resource control connection release message to the terminal device if the automatic change response message is an automatic change failure message. A method according to claim 7, wherein the RRC connection release message comprises: indication information of a supported network slice from a neighboring cell of a source cell, indication information of a supported network slice from a TA / RA to which the neighbor cell of the source cell belongs, or information about a supported network slice from a base station neighboring the source base station. 9. Communication method, comprising: receive, by a target base station, an automatic change request from a source base station, where the change request Petition 870190095647, of 09/24/2019, p. 177/212 3/16 automatic is used to request the automatic change of a session from a terminal device from the source base station to the target base station, and the automatic change request comprises an identifier of a session requested to be changed automatically and information from indication of a network slice corresponding to the session; and sending, through the target base station, an automatic change response message to the source base station, wherein the automatic change response message comprises rejection indication information, and rejection indication information is used to indicate cause information corresponding to a session, which is rejected by the target base station due to a network slice, from the requested session to be changed automatically. A method according to claim 9, wherein the session requested to be changed automatically comprises a first session, or the session requested to be changed automatically comprises the first session and a second session; and a network slice corresponding to the first session is supported by the target base station, and a network slice corresponding to the second session is not supported by the target base station. 11. Method according to claim 9 or 10, in which the cause information is that: the target base station does not support a network slice corresponding to the rejected session, or a resource is not available for a network slice that is supported by the target base station and corresponding to the rejected session. A method according to any one of claims 9 to 11, wherein the automatic change response message further comprises retransmission indication information corresponding to the session that is rejected by the target base station, and the retransmission indication information. corresponding to the session are used to indicate whether the terminal device is allowed to route, to a supported network slice from the target base station, a stream of data from the rejected session. 13. Method according to any of claims 9 to 12, wherein if the auto-change reply message is a message Petition 870190095647, of 09/24/2019, p. 178/212 4/16 automatic change request acknowledgment, the automatic change request acknowledgment message will additionally comprise a rejected carrier identifier or a rejected data stream identifier of the requested session to be automatically changed. Method according to any one of claims 9 to 13, further comprising: receiving an automatic change acknowledgment message from the target device from the target base station; send, on the target base station, a path switching request to a primary network device, where the path switching request comprises a session identifier accepted by the target base station and a session identifier rejected by the station target base; and receiving, by the target base station, a path switching request response message from the primary network device, wherein the path switching request response message comprises a session identifier so that path switching is performed. completed successfully. 15. The method of claim 14, wherein the path switching request further comprises indication information of the network slice corresponding to the session that is rejected by the target base station. 16. Communication method, comprising: receive, by a primary network device, a path switch request from a target base station, where the path switch request comprises a session identifier that is accepted by the target base station and a session identifier which is rejected by the target base station; perform, by the main network device, switching the trajectory of the accepted session, and disable or release the rejected session; and sending, via the main network device, a path switching request response message to the target base station, wherein the path switching request response message comprises Petition 870190095647, of 09/24/2019, p. 179/212 5/16 a session identifier for path switching to complete successfully. 17. Communication method, comprising: receive, by a terminal device, an RRC radio resource control connection release message from a source base station; and release, via the terminal device, an RRC connection; wherein the RRC connection release message comprises indication information of a supported network slice from a neighboring cell of a source cell, indication information of a supported network slice from a TA / RA which the neighboring cell of the source cell belongs to, or information about a supported network slice from a base station neighboring the source base station. 18. Base station, wherein the base station is a source base station, and the source base station comprises a processor and a transceiver; the processor sends an automatic change request to a target base station using the transceiver, where the automatic change request is used to request the automatic change of a session from a terminal device from the source base station to the base station target, and the automatic change request comprises an identifier of a session requested to be changed automatically and indication information of a network slice corresponding to the session; and the processor receives an automatic change response message from the target base station by using the transceiver, wherein the automatic change response message comprises rejection indication information, and rejection indication information is used to indicate rejection information. cause corresponding to a session, which is rejected by the target base station due to a network slice, from the session requested to be changed automatically. 19. Base station, according to claim 18, wherein the session requested to be changed automatically comprises a first session, or the session requested to be changed automatically comprises the first session and a second session; and a network slice corresponding to the first session is supported by the target base station, and a network slice corresponding to the second session Petition 870190095647, of 09/24/2019, p. 180/212 6/16 is not supported by the target base station. 20. Base station according to claim 18 or 19, wherein the cause information is that: the target base station does not support a network slice corresponding to the rejected session, or a resource is not available for a network slice that is supported by the target base station and corresponding to the rejected session. 21. Base station according to any one of claims 18 to 20, wherein if the automatic change response message is an automatic change request acknowledgment message, the automatic change response message further comprises indication information retransmission information corresponding to the session that is rejected by the target base station, and the relay indication information corresponding to the session will be used to indicate whether the terminal device is allowed to route, to a supported network slice of the target base station, a session data stream rejected. 22. Base station according to claim 21, further comprising: the processor sends an automatic change command to the terminal device using the transceiver if the automatic change response message is an automatic change request acknowledgment message, where the automatic change command comprises the corresponding retransmission indication information to the session that is rejected by the target base station. 23. Base station according to any one of claims 18 to 20, in which if the automatic change response message is an automatic change failure message, the processor sends a remote resource control connection release message. RRC radio to the terminal device by using the transceiver. 24. Base station according to claim 23, wherein the RRC connection release message comprises indication information of a supported network slice from a neighboring cell of a source cell, indication information of a supported network slice of a TA / RA to which Petition 870190095647, of 09/24/2019, p. 181/212 7/16 the neighbor cell of the source cell belongs to, or information about, a supported network slice of a base station neighboring the source base station. 25. Base station, wherein the base station is a target base station, and the target base station comprises a processor and a transceiver; the processor receives an automatic change request from a source base station by using the transceiver, where the automatic change request is used to request the automatic change of a session from a terminal device from the source base station to the base station target, and the automatic change request comprises an identifier of a session requested to be changed automatically and indication information of a network slice corresponding to the session; and the processor sends an automatic change response message to the source base station by using the transceiver, where the automatic change response message comprises rejection indication information, and rejection indication information is used to indicate information of cause corresponding to a session, which is rejected by the target base station due to a network slice, from the session requested to be changed automatically. 26. Base station according to claim 25, wherein the session requested to be changed automatically comprises a first session, or the session requested to be changed automatically comprises the first session and a second session; and a network slice corresponding to the first session is supported by the target base station, and a network slice corresponding to the second session is not supported by the target base station. 27. Base station according to claim 25 or 26, wherein the cause information is that: the target base station does not support a network slice corresponding to the rejected session, or a resource is not available for a network slice that is supported by the target base station and corresponding to the rejected session. 28. Base station according to any one of claims 25 to 27, wherein the automatic change response message comprises Petition 870190095647, of 09/24/2019, p. 182/212 8/16 additionally relay indication information corresponding to the session that is rejected by the target base station, and the relay indication information corresponding to the session is used to indicate whether the terminal device is allowed to route to a supported network slice from the target base station, a stream of rejected session data. 29. Main network device, wherein the main network device comprises a processor and a transceiver; the processor receives a path switching request from a target base station by using the transceiver, where the path switching request comprises a session identifier that is accepted by the target base station and a session identifier that is rejected by the target base station; the processor is configured to change the trajectory of the accepted session, and to deactivate or release the rejected session; and the processor sends a path switch request response message to the target base station using the transceiver, where the path switch request response message comprises a session identifier for path switching to complete. with success. 30. Terminal device, wherein the terminal device comprises a processor and a transceiver; the processor receives an RRC radio resource control connection release message from a source base station by using the transceiver; and the processor releases an RRC connection, wherein the RRC connection release message comprises indication information of a supported network slice from a neighboring cell of a source cell, indication information of a supported network slice from a TA / RA to which the neighboring cell of the source cell belongs, or information about a supported network slice from a base station neighboring the source base station. 31. The method of claim 16, wherein the path switch request message further comprises cause information corresponding to the session that is rejected by the target base station. Petition 870190095647, of 09/24/2019, p. 183/212 9/16 32. The method of claim 31, wherein the cause information is that: the target base station does not support a network slice corresponding to the rejected session. 33. The method of claim 32, wherein performing, by the main network device, switching the trajectory of the accepted session, and deactivating or releasing the rejected session, comprise: perform, by the main network device, the release of the session which is rejected by the fact that the target base station does not support the network slice corresponding to the rejected session. 34. Communication method, comprising: send, through a target base station, a path switch request to a primary network device, where the path switch request comprises a session identifier that is accepted by the target base station and a session identifier which is rejected by the target base station; and receiving, by the target base station, a path switching request response message sent by the main network device, wherein the path switching response response message comprises a session identifier for path switching to be performed. completed successfully. 35. The method of claim 34, wherein the path switch request response message further comprises: cause information corresponding to the session that is rejected by the target base station. 36. The method of claim 35, wherein the cause information is that: the target base station does not support a network slice corresponding to the rejected session. 37. The method of any one of claims 34 to 36, wherein prior to the sending, by a target base station, of a path switching request to a main network device, the method further comprises: receive, by the target base station, a request for automatic switching from a source base station; and Petition 870190095647, of 09/24/2019, p. 184/212 10/16 perform, by the target base station, admission control based on a support state of the network slice, a resource usage state, and the automatic change request. 38. The method of any one of claims 34 to 36, wherein prior to the sending, by a target base station, of a path switching request to a main network device, the method further comprises: receive, from the target base station, an automatic change request from a source base station, where the automatic change request is used to request the automatic change of a session from a terminal device from the source base station to the source base station target base, and the automatic change request comprises an identifier of a session requested to be automatically changed and indication information of a network slice corresponding to the session; and rejecting the session from the target base station if the target base station does not support the network slice corresponding to the session. 39. The method of claim 38, wherein the network slice indication information is S-NSSAI single network slice selection assistance information. 40. The method of claim 38 or 39, wherein the session requested to be changed automatically comprises a first session and a second session; and a network slice corresponding to the first session is supported by the target base station, and a network slice corresponding to the second session is not supported by the target base station. 41. The method of any one of claims 34 to 40, wherein the method further comprises: sending, by the target base station, an automatic change acknowledgment message to the source base station, wherein at least one stream session data, which is accepted by the target base station, is rejected. 42. The method of claim 41, wherein the automatic change request acknowledgment message further comprises information used to indicate a reason for rejecting at least one data stream. Petition 870190095647, of 09/24/2019, p. 185/212 11/16 43. The method of claim 42, wherein the information used to indicate the reason for rejecting at least one data stream comprises any one of the following: multiple data stream identifier, no available resources, or a combination quality of service invalid QoS corresponding to data flows. 44. Communication method, comprising: receiving, by a base station, a message from a first main network device, wherein the message comprises indication information of a supported network slice for public terrestrial mobile network PLMN served by the first main network device; and selecting, by the base station using the referral information, a primary network device to serve a terminal device. 45. The method of claim 44, wherein the message is an AMF configuration update message. 46. The method of claim 44, wherein the message is an NG interface definition response. 47. The method of claim 46, wherein the method further comprises: sending, through the base station, a request for definition of the NG interface to the main network device. 48. The method of any one of claims 44 to 47, wherein the indication information of at least one supported network slice for the PLMN served by the main network device comprises: indication information of at least one network slice supported for each PLMN served by the primary network device. 49. The method of any one of claims 44 to 48, wherein the indication information of at least one supported network slice comprises: SNSSAI single network slice selection assistance information. 50. Communication method, comprising: determining, by a main network device, information indicating a supported network slice for a public terrestrial mobile network PLMN served by the main network device; and send, by the main network device, a second message to a base station, where the second message comprises the Petition 870190095647, of 09/24/2019, p. 186/212 12/16 indication of the supported network slice indication for the PLMN served by the main network device. 51. The method of claim 50, wherein the second message is an AMF configuration update message. 52. The method of claim 50, wherein the second message is an NG interface definition response. 53. The method of claim 52, wherein the method further comprises: receiving, by the main network device, an NG interface definition request sent by the base station. 54. The method of any one of claims 50 to 52, wherein the indication of the supported network slice for the PLMN served by the main network device is indication information of a supported network slice for each PLMN served by the primary network device. 55. Main network device according to claim 29, wherein the path switching request message further comprises cause information corresponding to the session which is rejected by the target base station. 56. Main network device according to claim 55, wherein the cause information is that: the target base station does not support a network slice corresponding to the rejected session. 57. Main network device according to claim 29, wherein the processor is specifically configured to perform the session release which is rejected by the fact that the target base station does not support the network slice corresponding to the rejected session. 58. Base station, comprising: a transmission unit, configured to send a path switching request to a primary network device, where the path switching request comprises a session identifier that is accepted by the base station and a session identifier that is rejected by the base station; and a receiving unit, configured to receive a path switching request response message sent by the primary network device, where the Petition 870190095647, of 09/24/2019, p. 187/212 13/16 path switching comprises a session identifier for path switching to be completed successfully. 59. Base station according to claim 58, wherein the path switching request response message further comprises: cause information corresponding to a session that is rejected by a target base station. 60. Base station according to claim 59, wherein the cause information is that: the target base station does not support a network slice corresponding to the rejected session. 61. Base station according to any one of claims 58 to 60, wherein the receiving unit is additionally configured to receive an automatic change request from a source base station; and the base station additionally comprises a processor, and the processor is configured to perform admission control based on a network slice support state, a resource usage state, and the automatic change request. 62. Base station according to any of claims 58 to 60, wherein the receiving unit is additionally configured to receive an automatic change request from a source base station, in which the automatic change request is used to request the automatic change of a session from a terminal device from the source base station to the base station, and the automatic change request comprises an identifier of a session requested to be changed automatically and indication information for a network slice corresponding to the session; and the base station additionally comprises a processor, and the processor is configured to reject the session if the base station does not support the network slice corresponding to the session. 63. Base station according to claim 62, wherein the network slice indication information is S-NSSAI single network slice selection assist information. 64. The method of claim 62 or 63, wherein the session Petition 870190095647, of 09/24/2019, p. 188/212 14/16 requested to be changed automatically comprises a first session and a second session; and a network slice corresponding to the first session is supported by the target base station, and a network slice corresponding to the second session is not supported by the target base station. 65. Base station according to any one of claims 58 to 64, wherein the transmission unit is additionally configured to send an automatic change acknowledgment message to the source base station, wherein at least one data stream of the session, which is accepted by the target base station, is rejected. 66. Base station according to claim 65, wherein the automatic change request acknowledgment message further comprises information used to indicate a reason for rejecting at least one data stream. 67. Base station according to claim 46, wherein the information used to indicate the reason for rejecting at least one data stream comprises any of the following: multiple data stream identifier, no resources available, or a combination of invalid QoS quality of service corresponding to the data flows. 68. Base station, comprising: a receiving unit, configured to receive a message sent by a first main network device, wherein the message comprises indication information of a supported network slice for a public terrestrial mobile network PLMN served by the first main network device; and a processing unit, configured to select, using the indication information, a main network device to serve a terminal device. 69. Base station according to claim 68, wherein the message is an AMF configuration update message. 70. Base station according to claim 68, wherein the message is an N2 interface definition response. 71. Base station according to claim 70, further comprising a transmission unit, wherein the unit Petition 870190095647, of 09/24/2019, p. 189/212 15/16 transmission is configured to send an N2 interface definition request to the primary network device. 72. Base station according to any one of claims 68 to 71, wherein the information indicating the supported network slice for the PLMN served by the main network device comprises: information indicating a supported network slice for each PLMN served by the main network device. 73. The method of any one of claims 68 to 72, wherein the network slice indication information comprises S-NSSAI single network slice selection assistance information. 74. Main network device, comprising: a processing unit, configured to determine indication information of a supported network slice for a public terrestrial mobile network PLMN served by the main network device; and a transmission unit, configured to send a second message to a base station, wherein the second message comprises the indication of the supported network slice for the PLMN served by the main network device. 75. Main network device according to claim 74, wherein the second message is an AMF configuration update message. 76. Main network device according to claim 74, wherein the second message is an NG interface definition response. 77. Main network device according to claim 76, further comprising a receiving unit, wherein the receiving unit is configured to receive an NG interface definition request sent by the base station. 78. Main network device according to any one of claims 74 to 77, wherein the indication of the supported network slice for the PLMN served by the main network device is indication information of a supported network slice for each PLMN served by the main network device. 79. Communication device, configured to carry out the method as defined in any one of claims 1 to 17, claims 31 Petition 870190095647, of 09/24/2019, p. 190/212 16/16 to 54, or claim 73. 80. Computer-readable storage media, where the computer-readable storage media stores an instruction, and when the instruction runs on a computer, the computer is able to perform the method as defined in any of claims 1 to 17, claims 31 to 54, or claim 73.